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with  care. 

The  University  of  Connecticut 
Libraries,  Starrs 


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DISCOURSES  ^^^ 

BIOLOGICAL  AND  GEOLOGICAL  ^^ 


ESSAYS 


BY 

THOMAS   H.    HUXLEY 


NEW    YORK 
D.    APPLETON    AND    COMPANY 

1896 


Authorized  Edition. 


rHEFACE 

The  contents  of  the  present  volume,  with  three 
exceptions,  are  either  popular  lectures,  or  addresses 
delivered  to  scientific  bodies  with  which  I  have 
been  officially  connected.  I  am  not  sure  which 
gave  me  the  more  trouble.  For  I  have  not  been 
one  of  those  fortunate  persons  who  are  able  to 
regard  a  popular  lecture  as  a  mere  hers  dCceuvre, 
unworthy  of  being  ranked  among  the  serious  efforts 
of  a  philosopher;  and  who  keep  their  fame  as 
scientific  hierophants  unsullied  by  attempts — at 
least  of  the  successful  sort — to  be  understanded 
of  the  people. 

On  tlie  contrary,  I  found  that  the  task  of 
putting  the  truths  learned  in  the  field,  the 
laboratory  and  the  museum,  into  language  which, 
without  bating  a  jot  of  scientific  accuracy  shall  be 
generally  intelligible,  taxed  such  scientific  and 
literary  faculty  as  I  possessed  to  the  uttermost; 
indeed  my  experience  has  furnished  me  with  no 
better  corrective  of  the  tendency  to  scholastic 
pedantry  Avhich  besots  all  those  who  are  absorbed 


VI  PREFACE 

in  pursuits  remote  from  the  common  ways  of  men, 
and  become  habituated  to  think  and  speak  in  the 
technical  dialect  of  their  own  little  world,  as  if 
there  were  no  other. 

If  the  popular  lecture  thus,  as  I  believe, 
finds  one  moiety  of  its  justification  in  the  self- 
disciphne  of  the  lecturer,  it  surely  finds  the 
other  half  in  its  effect  on  the  auditory.  For 
though  various  sadly  comical  experiences  of  the 
results  of  my  own  efforts  have  led  me  to  entertain 
a  very  moderate  estimate  of  the  purely  intellectual 
value  of  lectures ;  though  I  venture  to  doubt  if 
more  than  one  in  ten  of  an  average  audience 
carries  away  an  accurate  notion  of  what  the 
speaker  has  been  driving  at ;  yet  is  that  not 
equally  true  of  the  oratory  of  the  hustings,  of  the 
House  of  Commons,  and  even  of  the  pulpit  ? 

Yet  the  children  of  this  world  are  wise  in  their 
generation ;  and  both  the  politician  and  the  priest 
are  justified  by  results.  The  living  voice  has  an 
influence  over  human  action  altogether  indepen- 
dent of  the  intellectual  worth  of  that  which  it 
utters.  Many  years  ago,  I  was  a  guest  at  a  great 
City  dinner.  A  famous  orator,  endowed  with  a 
voice  of  rare  flexibihty  and  power ;  a  born  actor, 
ranging  with  ease  through  every  part,  from  refined 
comedy  to  tragic  unction,  was  called  upon  to  reply 
to  a  toast.  The  orator  was  a  very  busy  man,  a 
charming  conversationalist  and  by  no  means 
despised  a  good  dinner;  and^I  imagine,  rose  with- 


PREFACE  VU 

out  having  given  a  thouglit  to  what  he  was  going 
to  say.  The  rhythmic  roll  of  sound  was  admirable, 
the  gestures  perfect,  the  earnestness  impressive; 
nothing  was  lacking  save  sense  and,  occasionally, 
grammar.  When  the  speaker  sat  down  the 
applause  was  terrific  and  one  of  my  neighbours 
was  especially  enthusiastic.  So  when  he  had 
quieted  down,  I  asked  him  what  the  orator  had 
said.     And  he  could  not  tell  me. 

That  sagacious  person  John  Wesley,  is  reported 
to  have  replied  to  some  one  who  questioned  the 
propriety  of  his  adaptation  of  sacred  words  to 
extremely  secular  airs,  that  he  did  not  see  why  the 
Devil  should  be  left  in  possession  of  all  the  best 
tunes.  And  I  do  not  see  why  science  should  not 
turn  to  account  the  peculiarities  of  human  nature 
thus  exploited  by  other  agencies  :  all  the  more 
because  science,  by  the  nature  of  its  being,  can- 
not desire  to  stir  the  passions,  or  profit  by  the 
weaknesses,  of  human  nature.  The  most  zealous 
of  popular  lecturers  can  aim  at  nothing  more 
than  the  awakening  of  a  S3mipathy  for  abstract 
truth,  in  those  who  do  not  really  follow  his  argu- 
ments ;  and  of  a  desii*e  to  know  more  and  better  in 
the  few  who  do. 

At  the  same  time  it  must  be  admitted  that  the 
popularization  of  science,  whether  by  lecture  or 
essay,  has  its  drawbacks.  Success  in  this  depart- 
ment has  its  perils  for  those  who  succeed.  The 
"  people  who  fail "  take  their  revenge,  as  we  have 


nil  PREFACE 

recently  had  occasion  to  observe,  by  ignoring  all 
the  rest  of  a  man's  work  and  glibly  labelling  him 
a  mere  popularizer.-  If  the  falsehood  were  not  too 
glaring,  they  would  say  the  same  of  Faraday  and 
Helmholtz  and  Kelvin. 

On  the  other  hand,  of  the  affliction  caused  by 
persons  who  think  that  what  they  have  picked  up 
from  popular  exposition  qualifies  them  for  discuss- 
ing the  great  problems  of  science,  it  may  be  said, 
as  the  Radical  toast  said  of  the  power  of  the  Crown 
in  bygone  days,  that  it  "  has  increased,  is  increas- 
ino-,  and  ouscht  to  be  diminished."  The  oddities 
of  "  English  as  she  is  spoke  "  might  be  abundantly 
paralleled  by  those  of  "  Science  as  she  is  misunder- 
stood "  in  the  sermon,  the  novel,  and  the  leading 
article;  and  a  collection  of  the  grotesque  trav- 
esties of  scientific  conceptions,  in  the  shape  of 
essays  on  such  trifles  as  "  the  Nature  of  Life  "  and 
the  "  Origin  of  All  Things,"  which  reach  me,  from 
time  to  time,  might  well  be  bound  up  with  them. 

The  tenth  essay  in  this  volume  unfortunately 
brought  me,  I  will  not  say  into  collision,  but  into 
a  position  of  critical  remonstrance  with  regard 
to  some  charges  of  physical  heterodoxy,  brought 
by  my  distinguished  friend  Lord  Kelvin,  against 
British  Geology.  As  President  of  the  Geological 
Society  of  London  at  that  time  (1869),  I  thought 
I  might  venture  to  plead  that  we  were  not  such 
heretics  as  we  seemed  to  be;    and  that,  even  if 


PREFACE  IX 

we  were,  recantation  would  not  affect  the 
question  of  evolution. 

I  am  glad  to  see  that  Lord  Kelvin  has  just 
reprinted  his  reply  to  my  plea,^  and  I  refer  the 
reader  to  it.  I  shall  not  presume  to  question  any- 
thing, that  on  such  ripe  consideration,  Lord  Kelvin 
has  to  say  upon  the  physical  problems  involved. 
But  I  may  remark  that  no  one  can  have  asserted 
more  strongly  than  I  have  done,  the  necessity 
of  looking  to  physics  and  mathematics,  for  help 
in  regard  to  the  earhest  history  of  the  globe. 
(See  pp.  108  and  109  of  this  volume.) 

And  I  take  the  opportunity  of  repeating  the 
opinion,  that,  whether  what  we  call  geological 
time  has  the  lower  limit  assigned  to  it  by  Lord 
Kelvin,  or  the  higher  assumed  by  cth3r  philoso- 
phers; whether  the  germs  of  all  living  things 
have  originated  in  the  globe  itself,  or  whether 
they  have  been  imported  on,  or  in,  meteorites 
from  without,  the  problem  of  the  origin  of  those 
successive  Faunae  and  Florae  of  the  earth,  the 
existence  of  which  is  fully  demonstrated  by 
paleontology  remains  exactly  where  it  was. 

For  I  think  it  will  be  admitted,  that  the  germs 
brought  to  us  by  meteorites,  if  any,  were  not  ova 
of  elephants,  nor  of  crocodiles ;  not  cocoa-nuts  nor 
acorns ;  not  even  eggs  of  shell-fish  and  corals ; 
but  only  those  of  the  lowest  forms  of  animal  and 
vegetable  life.  Therefore,  since  it  is  proved  that, 
^  Popular  Lectures  and  Addresses.    II.    Macmillan  and  Co.  1894, 


Z  PREFACE 

from  a  very  remote  epoch  of  geological  time,  the 
earth  has  been  peopled  by  a  continual  succession 
of  the  higher  forms  of  animals  and  plants,  these 
either  must  have  been  created,  or  they  have  arisen 
by  evolution.  And  in  respect  of  certain  groups  of 
animals,  the  well-established  facts  of  paleontology 
leave  no  rational  doubt  that  they  arose  by  the 
latter  method. 

In  the  second  place,  there  are  no  data  what- 
ever, which  justify  the  biologist  in  assigning 
any,  even  approximately  definite,  period  of  time, 
either  long  or  short,  to  the  evolution  of  one 
species  from  another  by  the  process  of  variation 
and  selection.  In  the  ninth  of  the  following 
essays,  I  have  taken  pains  to  prove  that  the  change 
of  animals  has  gone  on  at  very  different  rates  in 
different  groups  of  living  beings ;  that  some  types 
have  persisted  with  little  change  from  the  paleo- 
zoic epoch  till  now,  while  others  have  changed 
rapidly  within  the  limits  of  an  epoch.  In  1862 
(see  below  p.  303,  304)  in  1863  (vol.  IL,  p.  461) 
and  again  in  1864  {ibid.,  p.  89 — 91)  I  argued,  not 
as  a  matter  of  speculation,  but,  from  paleonto- 
logical  facts,  the  bearing  of  which  I  believe,  up  to 
that  time,  had  not  been  shown,  that  any  ade- 
quate hypothesis  of  the  causes  of  evolution  must 
be  consistent  with  progression,  stationariness  and 
retrogression,  of  the  same  type  at  different  epochs ; 
of  different  types  in  the  same  epoch ;  and  that 
Dal'^vin's  hypothesis  fulfilled  these  conditions. 


PREFACE  XI 

According  to  that  hypothesis,  two  factors  are  at 
work,  variation  and  selection.  Next  to  nothing  is 
known  of  the  causes  of  the  former  process ;  nothing 
whatever  of  the  time  required  for  the  production 
of  a  certain  amount  of  deviation  from  the  existing 
type.  And,  as  respects  selection,  which  operates 
by  extinguishing  all  but  a  small  minority  of 
variations,  we  have  not  the  slightest  means  of 
estimating  the  rapidity  with  which  it  does  its 
work.  All  that  we  are  justified  in  saying  is  that 
the  rate  at  which  it  takes  place  may  vary  almost 
indefinitely.  If  the  famous  paint-root  of  Florida, 
which  kills  white  pigs  but  not  black  ones,  were 
abundant  and  certain  in  its  action,  black  pigs 
might  be  substituted  for  white  in  the  course  of 
two  or  three  years.  If,  on  the  other  hand,  it  was 
rare  and  uncertain  in  action,  the  white  pigs  might 
linger  on  for  centuries. 

T.  H.  Huxley. 


HoDESLEA,  Eastbourne, 
April.  1894. 


CONTENTS 


I 

PAGE 

ON    A   PIECE   OF   CHALK  [1868] 1 

(A  Lecture  delivered  to  the  working  men  of 
Norwich  during  the  meeting  of  the  British 
Association.) 


II 

THE   PROBLEMS   OF   THE   DEEP    SEA  [1873] 37 


III 

on  rome  of  the  "results  of  the  expedition  of  h.m.s, 

•'challenger"  [1875] 69 


IV 

YEAST    [1871] 110 


XIV  CONTENTS 

V 

PAGE 

ON    THE   FORMATION    OF   COAL    [1870] 137 

(A    Lecture   delivered   at   the    Philosophical 
Institute,  Bradford. ) 


VI 

ON   THE   BORDER   TERRITORY   BETWEEN   THE   ANIMAL   AND 

THE  VEGETABLE   KINGDOMS    [1876] 162 

(A  Friday  evening  Lecture  delivered  at  the 
Koyal  Institution.) 

VII 

A    LOBSTER  ;    OR,    THE  STUDY  OF  ZOOLOGY   [1861]  ....     196 

(A  Lecture  delivered  at  the  South  Kensington 
Museum.) 

VIII 

BIOGENESIS    AND    ABIOGENESIS    [1870] 229 

(The  Pi-esidential  Address  to  the  Meeting  of 
the  British  Association  for  the  Advance- 
ment of  Science  at  Liverpool.) 


IX 

GEOLOGICAL    CONTEMPORANEITY    AND    PERSISTENT    TYPES 

OF    LIFE    [1862] 272 

(Address  to  the  Geologi^^al  Society  on  behalf 
of  the  President  by  one  of  the  Secretaries, ) 


CONTENTS  XV 

X 

PACK 

GEOLOGICAL   EEFORM    [1869] 305 

(Presidential     Address     to     the     Geological 
Society.) 

XI 

FAL^)NTOLOGY   AND   THE   DOCTRINE  OF  EVOLUTION  [1870]     340 

(Presidential    Address     to     the     Geological 
Societ  J'. ) 


ON  A  PIECE  OF  CHALK 

[1868] 

If  a  well  were  sunk  at  our  feet  in  the  midst  of 
the  city  of  Norwich,  the  diggers  would  very  soon 
find  themselves  at  work  in  that  white  substance 
almost  too  soft  to  be  called  rock,  with  which  we 
are  all  familiar  as  "  chalk." 

Not  only  here,  but  over  the  whole  county  of 
Norfolk,  the  well-sinker  might  carry  his  shaft 
down  many  hundred  feet  without  comiug  to  the 
end  of  the  chalk ;  and,  on  the  sea-coast,  where 
the  waves  have  pared  away  the  face  of  the  land 
which  breasts  them,  the  scarped  faces  of  the  high 
cliffe  are  often  wholly  formed  of  the  same  material. 
Northward,  the  chalk  may  be  followed  as  far  as 
Yorkshire  ;  on  the  south  coast  it  appears  abruptly 
in  the  picturesque  western  bays  of  Dorset,  and 
breaks  into  the  Needles  of  the  Isle  of  Wight ; 
while  on  the  shores  of  Kent  it  supplies  that  long 

187 


2  ON   A   PIECE   OF   CHALK  1 

line  of  white  cliffs  to  which  England  owes  her 
name  of  Albion. 

Were  the  thin  soil  which  covers  it  all  washed 
away,  a  curved  band  of  white  chalk,  here  broader, 
and  there  narrower,  might  be  followed  diagonally 
across  England  from  Lulworth  in  Dorset,  to  Flam- 
borough  Head  in  Yorkshire — a  distance  of  over 
280  miles  as  the  crow  flies.  From  this  band  to 
the  North  Sea,  on  the  east,  and  the  Channel,  on 
the  south,  the  chalk  is  largely  hidden  by  other 
deposits ;  but,  except  in  the  Weald  of  Kent  and 
Sussex,  it  enters  into  the  very  foundation  of  all 
the  south-eastern  counties. 

Attaining,  as  it  does  in  some  places,  a  thickness 
of  more  than  a  thousand  feet,  the  English  chalk 
must  be  admitted  to  be  a  mass  of  considerable 
magnitude.  Nevertheless,  it  covers  but  an  insig- 
nificant portion  of  the  whole  area  occupied  by  the 
chalk  formation  of  the  globe,  much  of  which  has 
the  same  general  characters  as  ours,  and  is  found 
in  detached  patches,  some  less,  and  others  more 
extensive,  than  the  English.  Chalk  occurs  in 
north-west  Ireland  ;  it  stretches  over  a  large  part 
of  France, — the  chalk  which  underlies  Paris  being, 
in  fact,  a  continuation  of  that  of  the  London  basin ; 
it  runs  through  Denmark  and  Central  Europe,  and 
extends  southward  to  North  Africa;  while  east- 
ward, it  appears  in  the  Crimea  and  in  Syria,  and 
may  be  traced  as  far  as  the  shores  of  the  Sea  of 
Aral,  in  Central  Asia.     If  all  the  points  at  which 


I  ON   A  PIECE  OF   CHALK  3 

true  clialk  occurs  were  circumscribed,  they  would 
lie  within  an  irregular  oval  about  3,000  miles  in 
long  diameter — the  area  of  which  would  be  as 
great  as  that  of  Europe,  and  would  many  times 
exceed  that  of  the  largest  existing  inland  sea — 
the  Mediterranean. 

Thus  the  chalk  is  no  unimportant  element  in 
the  masonry  of  the  earth's  crust,  and  it  impresses 
a  peculiar  stamp,  varying  with  the  conditions  to 
which  it  is  exposed,  on  the  scenery  of  the  districts 
in  which  it  occurs.  The  undulating  downs  and 
rounded  coombs,  covered  with  sweet-grassed  turf, 
of  our  inland  chalk  country,  have  a  peacefully 
domestic  and  mutton-suggesting  prettiness,  but 
can  hardly  be  called  either  grand  or  beautiful. 
But  on  our  southern  coasts,  the  wall-sided  cliffs, 
many  hundred  feet  high,  with  vast  needles  and 
pinnacles  standing  out  in  the  sea,  sharp  and 
solitary  enough  to  serve  as  perches  for  the  wary 
cormorant,  confer  a  wonderful  beauty  and  grandeur 
upon  the  chalk  headlands.  And,  in  the  East, 
chalk  has  its  share  in  the  formation  of  some  of 
the  most  venerable  of  mountain  ranges,  such  as 
the  Lebanon. 

What  is  this  wide-spread  component  of  the 
surface  of  the  earth  ?  and  whence  did  it  come  ? 

You  may  think  this  no  very  hopeful  inquiry. 
You  may  not  unnaturally  suppose  that  the 
attempt  to  solve  such  problems  as  these  can  lead 


4  ON   A   riECE   OF   CHALK  I 

to  no  result,  save  that  of  entangling  the  inquirer 
in  vague  speculations,  incapable  of  refutation  and 
of  verification.  If  such  were  really  the  case,  I 
should  have  selected  some  other  subject  than  a 
"  piece  of  chalk  "  for  my  discourse.  But,  in  truth, 
after  much  deliberation,  I  have  been  unable  to 
think  of  any  topic  which  would  so  well  enable  me 
to  lead  you  to  see  how  solid  is  the  foundation 
upon  which  some  of  the  most  startling  conclusions 
of  ph3'sical  science  rest. 

A  great  chapter  of  the  history  of  the  world  is 
written  in  the  chalk.  Few  passages  in  the  history 
of  man  can  be  supported  by  such  an  overwhelm- 
ing mass  of  direct  and  indirect  evidence  as  that 
which  testifies  to  the  truth  of  the  fragment  of  the 
history  of  the  globe,  which  I  hope  to  enable  you 
to  read,  with  your  own  eyes,  to-night.  Let  me 
add,  that  few  chapters  of  human  history  have  a 
more  profound  significance  for  ourselves.  I  weigh 
my  words  well  when  I  assert,  that  the  man  who 
should  know  the  true  history  of  the  bit  of  chalk 
which  every  carpenter  carries  about  in  his 
breeches-pocket,  though  ignorant  of  all  other 
history,  is  likely,  if  he  will  think  his  knowledge 
out  to  its  ultimate  results,  to  have  a  truer,  and 
therefore  a  better,  conception  of  this  wonderful 
universe,  and  of  man's  relation  to  it,  than  the 
most  learned  student  who  is  deep-read  in  the 
records  of  humanity  and  ignorant  of  those  of 
Nature. 


I  ON  A  PIECE   OF   CHALK  5 

The  language  of  the  chalk  is  not  hard  to  learn, 
not  nearly  so  hard  as  Latin,  if  you  only  want  to 
get  at  the  broad  features  of  the  story  it  has  to 
tell ;  and  I  propose  that  we  now  set  to  work  to 
spell  that  story  out  together. 

We  all  know  that  if  we  "  burn "  chalk  the 
result  is  quicklime.  Chalk,  in  fact,  is  a  compound 
of  carbonic  acid  gas,  and  lime,  and  when  you 
make  it  very  hot  the  carbonic  acid  flies  away  and 
the  Kme  is  left.  By  this  method  of  procedure 
we  see  the  lime,  but  we  do  not  see  the  carbonic 
acid.  If,  on  the  other  hand,  you  were  to  powder 
a  little  chalk  and  drop  it  into  a  good  deal  of  strong 
vinegar,  there  would  be  a  great  bubbling  and 
fizzing,  and,  finally,  a  clear  liquid,  in  which  no 
sign  of  chalk  would  appear.  Here  you  see  the 
carbonic  acid  in  the  bubbles ;  the  lime,  dissolved 
in  the  vinegar,  vanishes  from  sight.  There  are  a 
great  many  other  ways  of  showing  that  chalk  is 
essentially  nothing  but  carbonic  acid  and  quick- 
lime. Chemists  enunciate  the  result  of  all  the 
experiments  which  prove  this,  by  stating  that 
chalk  is  almost  wholly  composed  of  "carbonate 
of  lime." 

It  is  desirable  for  us  to  start  from  the  knowledge 
of  this  fact,  though  it  may  not  seem  to  help  us 
very  far  towards  what  we  seek.  For  carbonate 
of  lime  is  a  widely-spread  substance,  and  is  met 
with  under  very  various  conditions.  All  sorts  of 
limestones  are  composed  of  more  or    less    pure 


6  ON  A  PIECE  OF   CHALK  I 

carbonate  of  lime.  The  cinist  which  is  often 
deposited  by  waters  which  have  drained  through 
limestone  rocks,  in  the  form  of  what  are  called 
stalagmites  and  stalactites,  is  carbonate  of  lime. 
Or,  to  take  a  more  familiar  example,  the  fur  on 
the  inside  of  a  tea-kettle  is  carbonate  of  lime ; 
and,  for  an}i}hing  chemistry  tells  us  to  the  con- 
trary, the  chalk  might  be  a  kind  of  gigantic  fur 
upon  the  bottom  of  the  earth-kettle,  which  is 
kept  pretty  hot  below. 

Let  us  try  another  method  of  making  the  chalk 
tell  us  its  own  history.  To  the  unassisted  eye 
chalk  looks  simply  hke  a  very  loose  and  open 
kind  of  stone.  But  it  is  possible  to  grind  a  slice 
of  chalk  down  so  thin  that  you  can  see  through 
it — until  it  is  thin  enough,  in  fact,  to  be  examined 
with  any  magnifying  power  that  may  be  thought 
desirable.  A  thin  slice  of  the  fur  of  a  kettle 
might  be  made  in  the  same  way.  If  it  were 
examined  microscopically,  it  would  show  itself  to 
be  a  more  or  less  distinctly  laminated  mineral  sub- 
stance, and  nothing  more. 

•But  the  slice  of  chalk  presents  a  totally  different 
appearance  when  placed  under  the  microscope. 
The  general  mass  of  it  is  made  up  of  very  minute 
granules ;  but,  imbedded  in  this  matrix,  are  in- 
numerable bodies,  some  smaller  and  some  larger, 
but,  on  a  rough  average,  not  more  than  a 
hundredth  of  an  inch  in  diameter,  having  a  well- 
defined  shape  and  structure.     A   cubic   inch   of 


I  ON  A  PIECE  OF  CHALK  7 

some  specimens  of  chalk  may  contain  hundreds  of 
thousands  of  these  bodies,  compacted  together 
with  incalculable  millions  of  the  granules. 

The  examination  of  a  transparent  slice  gives  a 
good  notion  of  the  manner  in  which  the  com- 
ponents of  the  chalk  are  arranged,  and  of  their 
relative  proportions.  But,  by  rubbing  up  some 
chalk  with  a  brush  in  water  and  then  pouring  off 
the  milky  fluid,  so  as  to  obtain  sediments  of 
different  degrees  of  fineness,  the  gi^anules  and 
the  minute  rounded  bodies  may  be  pretty  well 
separated  from  one  another,  and  submitted  to 
microscopic  examination,  either  as  opaque  or  as 
transparent  objects.  By  combining  the  views 
obtained  in  these  various  methods,  each  of  the 
rounded  bodies  may  be  proved  to  be  a  beautifully- 
constructed  calcareous  fabric,  made  up  of  a 
number  of  chambers,  communicating  freely  with 
one  another.  The  chambered  bodies  are  of 
various  forms.  One  of  the  commonest  is  some- 
thing like  a  badly-grown  raspberry,  being  formed 
of  a  number  of  nearly  globular  chambers  of 
different  sizes  congregated  together.  It  is  called 
Glohigerina,  and  some  specimens  of  chalk  consist 
of  little  else  than  Globigerhim  and  granules.  Let 
us  fix  our  attention  upon  the  Glohigerina.  It  is 
the  spoor  of  the  game  we  are  tracking.  If  we  can 
learn  what  it  is  and  what  are  the  conditions  of  its 
existence,  we  shall  see  our  way  to  the  origin  and 
past  history  of  the  chalk 


8  ON   A   PIECE  OF   CHALK  I 

A  suggestion  which  may  naturally  enough  pre- 
sent itself  is,  that  these  curious  bodies  are  the 
result  of  some  process  of  aggregation  which  has 
taken  place  in  the  carbonate  of  lime ;  that,  just 
as  in  winter,  the  rime  on  our  windows  simulates 
the  most  delicate  and  elegantly  arborescent  foliage 
— proving  that  the  mere  mineral  water  may, 
under  certain  conditions,  assume  the  outward 
form  of  organic  bodies — so  this  mineral  substance, 
carbonate  of  lime,  hidden  away  in  the  bowels  of 
the  earth,  has  taken  the  shape  of  these  chambered 
bodies.  I  am  not  raising  a  merely  fanciful  and 
unreal  objection.  Very  learned  men,  in  former 
days,  have  even  entertained  the  notion  that  all  the 
formed  things  found  in  rocks  are  of  this  nature ; 
and  if  no  such  conception  is  at  present  held  to  be 
admissible,  it  is  because  long  and  varied  ex- 
perience has  now  shown  that  mineral  matter 
never  does  assume  the  form  and  structure  we  find 
in  fossils.  If  any  one  were  to  try  to  persuade 
you  that  an  oyster-shell  (which  is  also  chiefly 
composed  of  carbonate  of  lime)  had  crystallized 
out  of  sea-water,  I  suppose  you  would  laugh  at 
the  absurdity.  Your  laughter  would  be  justified 
by  the  fact  that  all  experience  tends  to  show  that 
oyster-shells  are  formed  by  the  agency  of  oysters, 
and  in  no  other  way.  And  if  there  were  no  better 
reasons,  we  should  be  justified,  on  like  grounds, 
in  believing  that  Glohigerina  is  not  the  product  of 
anything  but  vital  activity. 


I  ON  A  PIECE  OF  CHALK  9 

Happily,  however,  better  evidence  in  proof  of 
the  organic  nature  of  the  GlohigerincB  than  that 
of  analogy  is  forthcoming.  It  so  happens  that 
calcareous  skeletons,  exactly  similar  to  the 
Glohigerince  of  the  chalk,  are  being  formed,  at 
the  present  moment,  by  minute  hving  creatures, 
which  flourish  in  multitudes,  Hterally  more 
numerous  than  the  sands  of  the  sea-shore,  over  a 
large  extent  of  that  part  of  the  earth's  surface 
which  is  covered  by  the  ocean. 

The  history  of  the  discovery  of  these  living 
Glohigerince,  and  of  the  part  which  they  play  in 
rock  building,  is  singular  enough.  It  is  a 
discovery  which,  like  others  of  no  less  scientific 
importance,  has  arisen,  incidentally,  out  of  work 
devoted  to  very  different  and  exceedingly  practical 
interests.  When  men  first  took  to  the  sea,  they 
speedily  learned  to  look  out  for  shoals  and  rocks  ; 
and  the  more  the  burthen  of  their  ships  increased, 
the  more  imperatively  necessary  it  became  for 
sailors  to  ascertain  with  precision  the  depth  of 
the  waters  they  traversed.  Out  of  this  necessity 
grew  the  use  of  the  lead  and  sounding  line ;  and, 
ultimately,  marine-surve3dng,  which  is  the  re- 
cording of  the  form  of  coasts  and  of  the  depth 
of  the  sea,  as  ascertained  by  the  sounding-lead, 
upon  charts. 

At  the  same  time,  it  became  desirable  to  ascer- 
tain and  to  indicate  the  nature  of  the  sea-bottom, 
since  this  circumstance  gi'catly  affects  its  goodness 


10  ON   A   PIECE   OF   CHALK  I 

as  holding  ground  for  anchors.  Some  ingenious 
tar,  whose  name  deserves  a  better  fate  than  the 
oblivion  into  which  it  has  fallen,  attained  this 
object  by  "arming"  the  bottom  of  the  lead  with 
a  lump  of  grease,  to  which  more  or  less  of  the 
sand  or  mud,  or  broken  shells,  as  the  case  might 
be,  adhered,  and  was  brought  to  the  surface.  But, 
however  well  adapted  such  an  apparatus  might 
be  for  rough  nautical  purposes,  scientific  accuracy 
could  not  be  expected  from  the  armed  lead,  and 
to  remedy  its  defects  (especially  when  applied  to 
sounding  in  great  depths)  Lieut.  Brooke,  of  the 
American  Navy,  some  years  ago  invented  a  most 
ingenious  machine,  by  which  a  considerable  por- 
tion of  the  superficial  layer  of  the  sea-bottom  can 
be  scooped  out  and  brought  up  from  any  depth  to 
which  the  lead  descends.  In  1853,  Lieut.  Brooke 
obtained  mud  from  the  bottom  of  the  North 
Atlantic,  between  Newfoundland  and  the  Azores, 
at  a  depth  of  more  than  10,000  feet,  or  two  miles, 
by  the  help  of  this  sounding  apparatus.  The 
specimens  were  sent  for  examination  to  Ehrenberg 
of  Berlin,  and  to  Bailey  of  West  Point,  and  those 
able  microscopists  found  that  this  deep-sea  mud 
was  almost  entirely  composed  of  the  skeletons  of 
living  organisms — the  greater  proportion  of  these 
being  just  like  the  Glchigerinm  aheady  known  to 
occur  in  the  chalk. 

Thus  far,  the  work  had  been  carried  on  simply 
in  the  interests  of  science,  but  Lieut.  Brooke's 


I  ON  A  PIECE   OF   CHALK  11 

method  of  sounding  acquired  a  high  commercial 
value,  when  the  enterprise  of  laying  down  the 
telegraph-cable  between  this  country  and  the 
United  States  was  undertaken.  For  it  became  a 
matter  of  immense  importance  to  know,  not  only 
the  depth  of  the  sea  over  the  whole  line  along 
which  the  cable  was  to  be  laid,  but  the  exact 
nature  of  the  bottom,  so  as  to  guard  against 
chances  of  cutting  or  fraying  the  strands  of  that 
costly  rope.  The  Admiralty  consequently  ordered 
Captain  Dayman,  an  old  friend  and  shipmate  of 
mine,  to  ascertain  the  depth  over  the  whole  line 
of  the  cable,  and  to  bring  back  specimens  of  the 
bottom.  In  former  days,  such  a  command  as  this 
might  have  sounded  very  much  like  one  of  the 
impossible  things  which  the  young  Prince  in  the 
Fairy  Tales  is  ordered  to  do  before  he  can  obtain 
the  hand  of  the  Princess.  However,  in  the  months 
of  June  and  July,  1857,  my  friend  performed  the 
task  assigned  to  him  with  great  expedition  and 
precision,  without,  so  far  as  I  know,  having  met 
with  any  reward  of  that  kind.  The  specimens  of 
Atlantic  mud  which  he  procured  were  sent  to  me 
to  be  examined  and  reported  upon.^ 


^  See  Appendix  to  Captain  Dayman's  Deep-sea  SotmcUngs  in 
the  North  Atlantic  Ocean  hetioeen  Ireland  and  Ncvfoundland, 
made  in  H.M.S.  "  Cyclops."  Publislied  by  order  of  the  Lords 
Conrimissioners  of  the  Admiralty,  1858.  They  have  since 
formed  the  subject  of  an  elaborate  Memoir  by  Messrs.  Parker 
and  Jones,  published  in  the  Philosophical  Transactions  foi 
1865. 


12  ON   A  PIECE   OF   CHALK  I 

The  result  of  all  these  operations  is,  that  we 
know  the  contours  and  the  nature  of  the  surface- 
soil  covered  by  the  North  Atlantic  for  a  distance 
of  1,700  miles  from  east  to  west,  as  well  as  we 
know  that  of  any  part  of  the  dry  land.  It  is  a 
prodigious  plain — one  of  the  widest  and  most  even 
plains  in  the  world.  If  the  sea  were  drained  off, 
you  might  drive  a  waggon  all  the  way  from 
Valentia,  on  the  west  coast  of  Ireland,  to  Trinity 
Bay,  in  Newfoundland.  And,  except  upon  one 
sharp  incline  about  200  miles  from  Valentia,  I  am 
not  quite  sure  that  it  would  even  be  necessary  to 
put  the  skid  on,  so  gentle  are  the  ascents  and 
descents  upon  that  long  route.  From  Valentia 
the  road  would  lie  down-hill  for  about  200  miles 
to  the  point  at  which  the  bottom  is  now  covered 
by  1,700  fathoms  of  sea-water.  Then  would  come 
the  central  plain,  more  than  a  thousand  miles  wide, 
the  inequalities  of  the  surface  of  which  would  be 
hardly  perceptible,  though  the  depth  of  water 
upon  it  now  varies  from  10,000  to  15,000  feet; 
and  there  are  places  in  which  Mont  Blanc  might 
be  sunk  without  showing  its  peak  above  water. 
Beyond  this,  the  ascent  on  the  American  side 
commences,  and  gradually  leads,  for  about  300 
miles,  to  the  Newfoundland  shore. 

Almost  the  whole  of  the  bottom  of  this  central 
plain  (which  extends  for  many  hundred  miles  in  a 
north  and  south  direction)  is  covered  by  a  fine 
mud,  which,  when  brought  to  the  surface,  dries 


I  ON  A  PIECE  OF   CHALK  13 

into  a  greyish  white  friable  substance.  You  can 
write  with  this  on  a  blackboard,  if  you  are  so 
inclined  ;  and,  to  the  eye,  it  is  quite  Hke  very  soft, 
gra3rish  chalk.  Examined  chemically,  it  proves  to 
be  composed  almost  wholly  of  carbonate  of  lime  ; 
and  if  you  make  a  section  of  it,  in  the  same  way 
as  that  of  the  piece  of  chalk  was  made,  and  view 
it  with  the  microscope,  it  presents  innumerable 
Globigerince  embedded  in  a  granular  matrix.  Thus 
this  deep-sea  mud  is  substantially  chalk.  I  say 
substantially,  because  there  are  a  good  many 
minor  differences ;  but  as  these  have  no  bearing  on 
the  question  immediately  before  us, — which  is  the 
nature  of  the  Glchigerince  of  the  chalk, — it  is  un- 
necessary to  speak  of  them. 

Glcbigerince  of  every  size,  from  the  smallest  to 
the  largest,  are  associated  together  in  the  Atlantic 
mud,  and  the  chambers  of  many  are  filled  by  a  soft 
animal  matter.  This  soft  substance  is,  in  fact,  the 
remains  of  the  creature  to  which  the  Glohigerina 
shell,  or  rather  skeleton,  owes  its  existence — and 
which  is  an  animal  of  the  simplest  imaginable 
description.  It  is,  in  fact,  a  mere  particle  of  living 
jelly,  without  defined  parts  of  any  kind — without 
a  mouth,  nerves,  muscles,  or  distinct  organs,  and 
only  manifesting  its  vitaHty  to  ordinary  observa- 
tion by  thrusting  out  and  retracting  from  all  parts  of 
its  surface,  long  filamentous  processes,  which  serve 
for  arms  and  legs.  Yet  this  amorphous  particle, 
devoid  of  everything  which,  in  the  higher  animals, 


14  ON   A   PIECE  OF   CHALK  1 

we  call  organs,  is  capable  of  feeding,  growing,  and 
multipljdng ;  of  separating  from  tlie  ocean  the 
small  proportion  of  carbonate  of  lime  which  is 
dissolved  in  sea-water ;  and  of  building  up  that 
substance  into  a  skeleton  for  itself,  according  to  a 
pattern  which  can  be  imitated  by  no  other  known 
agency. 

The  notion  that  animals  can  live  and  flourish  in 
the  sea,  at  the  vast  depths  from  which  apparently 
living  GlGhigerinm  have  been  brought  up,  does 
not  agree  very  well  with  our  usual  conceptions  re- 
specting the  conditions  of  animal  life  ;  and  it  is  not 
so  absolutely  impossible  as  it  might  afc  first  sight 
appear  to  be,  that  the  Globigerince  of  the  Atlantic 
sea-bottom  do  not  live  and  die  where  they  are 
found. 

As  I  have  mentioned,  the  soundings  from  the 
great  Atlantic  plain  are  almost  entirely  made  up 
of  Glohigermce,  with  the  granules  which  have  been 
mentioned,  and  some  few  other  calcareous  shells ; 
but  a  small  percentage  of  the  chalky  mud — per- 
haps at  most  some  five  per  cent,  of  it — is  of  a 
different  nature,  and  consists  of  shells  and  skele- 
tons composed  of  silex,  or  pure  flint.  These 
silicious  bodies  belong  partly  to  the  lowly  vege- 
table organisms  which  are  called  Diatomacccc,  and 
partly  to .  the  minute,  and  extremely  simple, 
animals,  termed  Badiolaria.  It  is  quite  certain 
that  these  creatures  do  not  live  at  the  bottom  of 
the  ocean,  but  at  its  surface — where  they  may  be 


I  ON  A  PIECE  OF   CHALK  15 

obtained  in  prodigious  numbers  by  the  use  of  a 
properly  constructed  net.  Hence  it  follows  that 
these  silicious  organisms,  though  they  are  not 
heavier  than  the  lightest  dust,  must  have  fallen, 
in  some  cases,  through  fifteen  thousand  feet  of 
water,  before  they  reached  their  final  resting- 
place  on  the  ocean  fioor.  And  considering  how 
large  a  surface  these  bodies  expose  in  proportion 
to  their  weight,  it  is  probable  that  they  occupy  a 
great  length  of  time  in  making  their  burial 
journey  from  the  surface  of  the  Atlantic  to  the 
bottom. 

But  if  the  Radiolaria  and  Diatoms  are  thus 
rained  upon  the  bottom  of  the  sea,  from  the 
superficial  layer  of  its  waters  in  which  they  pass 
their  lives,  it  is  obviously  possible  that  the 
GlobigerincB  may  be  similarly  derived ;  and  if  they 
were  so,  it  would  be  much  more  easy  to  under- 
stand how  they  obtain  their  supply  of  food  than 
it  is  at  present.  Nevertheless,  the  positive  and 
negative  evidence  all  points  the  other  way.  The 
skeletons  of  the  full-grown,  deep-sea  Glohigerince 
are  so  remarkabl}^  solid  and  heavy  in  proportion  to 
their  surface  as  to  seem  Httle  fitted  for  floating ; 
and,  as  a  matter  of  fact,  they  are  not  to  be  found 
along  with  the  Diatoms  and  Badiolaria  in  the 
uppermost  stratum  of  the  open  ocean.  It  has 
been  observed,  again,  that  the  abundance  of 
Glohigerince,  in  proportion  to  other  organisms,  of 
like  kind,  increases  with  the  depth  of  the  sea ;  and 


16  ON   A  PIECE   OF   CHALK  I 

that  deep-water  Globigerince  are  larger  than  those 
which  Hve  in  shallower  parts  of  the  sea  ;  and  such 
facts  negative  the  supposition  that  these  organisms 
have  been  swept  by  currents  from  the  shallows 
into  the  deeps  of  the  Atlantic.  It  therefore  seems 
to  be  hardly  doubtful  that  these  wonderful 
creatures  live  and  die  at  the  depths  in  which  they 
are  found.^ 

However,  the  important  points  for  us  are,  that 
the  living  Glohigerince  are  exclusively  marine 
animals,  the  skeletons  of  which  abound  at  the 
bottom  of  deep  seas ;  and  that  there  is  not  a 
shadow  of  reason  for  believing  that  the  habits  of 
the  Globigerince  of  the  chalk  differed  from  those 
of  the  existing  species.  But  if  this  be  true,  there 
is  no  escaping  the  conclusion  that  the  chalk  itself 
is  the  dried  mud  of  an  ancient  deep  sea. 

In  working  over  the  soundings  collected  by 
Captain  Dayman,  I  was  surprised  to  find  that 
many  of  what  I  have  called  the  "  granules  "  of  that 
mud  were  not,  as  one  might  have  been  tempted 

^  During  the  cruise  of  H.M.S.  Bulldog,  commanded  by  Sir 
Leopold  M'Clmtock,  in  1860,  living  star-fish  were  brought  uj), 
clinging  to  the  lowest  part  of  the  sounding-line,  from  a  depth 
of  1,260  fathoms,  midway  between  Cape  Farewell,  in  Green- 
land, and  the  Rockall  banks.  Dr.  Wallich  ascertained  that 
the  sea-bottom  at  this  point  consisted  of  the  ordinary  Globi- 
geriim  ooze,  and  that  the  stomachs  of  the  star-fishes  were  full 
of  Globigerince.  This  discovery  removes  all  objections  to  the 
existence  of  living  Globigerince  at  great  depths,  which  are  based 
upon  the  supposed  diffictilty  of  maintaining  animal  life  under 
snch  conditions  ;  and  it  throws  the  burden  of  proof  upon  those 
■who  object  to  the  supposition  that  the  Globigerince  live  and 
die  where  they  are  found. 


I  ON  A   PIECE   OF   CHALK  17 

to  think  at  first,  the  mere  powder  and  waste  of 
Globigerinm,  but  that  they  had  a  definite  form  and 
size.  I  termed  these  bodies  "  coccoliths"  and 
doubted  their  organic  nature.  Dr.  WalHch  verified 
my  observation,  and  added  the  interesting  dis- 
covery that,  not  unfrequently,  bodies  similar  to 
these  "  coccoliths  "  were  aggregated  together  into 
spheroids,  which  he  termed  "  ccccjspheres."  So  far 
as  we  knew,  these  bodies,  the  nature  of  which 
is  extremely  puzzling  and  problematical,  were 
peculiar  to  the  Atlantic  soundings.  But,  a  few 
years  ago,  Mr.  Sorby,  in  making  a  careful  examina- 
tion of  the  chalk  by  means  of  thin  sections  and 
otherwise,  observed,  as  Ehrenberg  had  done  before 
him,  that  much  of  its  granular  basis  possesses  a 
definite  form.  Comparing  these  formed  particles 
with  those  in  the  Atlantic  soundings,  he  found 
the  two  to  be  identical ;  and  thus  proved  that  the 
chalk,  like  the  surroundings,  contains  these  mys- 
terious coccoliths  and  coccospheres.  Here  was  a 
further  and  most  interesting  confirmation,  from 
internal  evidence,  of  the  essential  identity  of  the 
chalk  with  modem  deep-sea  mud.  Glohigerince, 
coccoliths,  and  coccospheres  are  found  as  the  chief 
constituents  of  both,  and  testify  to  the  general 
similarity  of  the  conditions  under  which  both  have 
been  formed.^ 

The  evidence  furnished  by  the  hewing,  facing, 

^  I  have  recently  traced  out  the  development  of  the  "cocco- 
lith:3 "  fi  cm  a  diameter  of  T-oVij-th  of  an  inch  up  to  their  largest 

188 


18  ON   A  PIECE  OF   CHALK  I 

and  superposition  of  the  stones  of  the  Pyramids, 
that  these  structures  were  built  by  men,  has  no 
greater  weight  than  the  evidence  that  the  chalk 
was  built  by  Glchigerince ;  and  the  belief  that 
those  ancient  pyramid-builders  were  terrestrial 
and  air-breathing  creatures  hke  ourselves,  is  not 
better  based  than  the  conviction  that  the  chalk- 
makers  lived  in  the  sea.  But  as  our  belief  in  the 
building  of  the  Pyramids  by  men  is  not  only 
grounded  on  the  internal  evidence  afforded  by 
.  these  structures,  but  gathers  strength  from  multi- 
tudinous collateral  proofs,  and  is  clinched  by  the 
total  absence  of  any  reason  for  a  contrary  belief; 
so  the  evidence  drawn  jfrom  the  Glchigerince  that 
the  chalk  is  an  ancient  sea-bottom,  is  fortified  by 
innumerable  independent  lines  of  evidence ;  and 
our  belief  in  the  truth  of  the  conclusion  to  which 
all  positive  testimony  tends,  receives  the  like 
negative  justification  from  the  fact  that  no  other 
hypothesis  has  a  shadow  of  foundation. 

It  may  be  worth  while  briefly  to  consider  a  few 
of  these  collateral  proofs  that  the  chalk  was  de- 
posited at  the  bottom  of  the  sea.  The  great 
mass  of  the  chalk  is  composed,  as  we  have  seen, 
of  the  skeletons  of  Glchigerince,  and  other  simple 
organisms,  imbedded  in  granular  matter.  Here 
and  there,  however,  this  hardened  mud  of   the 

size  (which  is  about  rsVoth),  and  no  longer  doubt  that  they 
are  produced  by  independent  organisms,  which,  like  the  Globi- 
gerince,  live  and  die  at  the  bottom  of  the  sea. 


I  ON    A   PIECE  OF   CHALK  '  19 

ancient  sea  reveals  tlie  remains  of  higher  aniraals 
which  have  hved  and  died,  and  left  their  hard 
parts  in  the  mud,  just  as  the  oysters  die  and 
leave  their  shells  behind  them,  in  the  mud  of  the 
present  seas. 

There  are,  at  the  present  day,  certain  groups  of 
animals  which  are  never  found  in  fresh  waters, 
being  unable  to  live  anywhere  but  in  the  sea. 
Such  are  the  corals ;  those  corallines  which  are 
called  Polyzoa ;  those  creatures  which  fabricate 
the  lamp-shells,  and  are  called  Brachicpcda ;  the 
pearly  Nautilus,  and  all  animals  allied  to  it ;  and 
all  the  forms  of  sea-urchins  and  star-fishes.  Not 
only  are  all  these  creatures  confined  to  salt  water 
at  the  present  day ;  but,  so  far  as  our  records  of 
the  past  go,  the  conditions  of  their  existence  have 
been  the  same :  hence,  their  occurrence  in  any 
deposit  is  as  strong  evidence  as  can  be  obtained, 
that  that  deposit  was  formed  in  the  sea.  Now 
the  remains  of  animals  of  all  the  kinds  which  have 
been  enumerated,  occur  in  the  chalk,  in  greater  or 
less  abundance ;  while  not  one  of  those  forms  of 
shell-fish  which  are  characteristic  of  fresh  water 
has  yet  been  observed  in  it. 

When  we  consider  that  the  remains  of  more 
than  three  thousand  distinct  species  of  aquatic 
animals  have  been  discovered  among  the  fossils  of 
the  chalk,  that  the  great  majority  of  them  are  of 
such  forms  as  are  now  met  with  only  in  the  sea, 
and  that  there  is  no  reason  to  believe  that  any 


20  ON   A  PIECE   OF   CHALK  I 

one  of  them  inhabited  fresh  water — the  collateral 
evidence  that  the  chalk  represents  an  ancient  sea- 
bottom  acquires  as  great  force  as  the  proof 
derived  from  the  nature  of  the  chalk  itself  I 
think  you  will  now  allow  that  I  did  not  overstate 
my  case  when  I  asserted  that  we  have  as  strong 
grounds  for  believing  that  all  the  vast  area  of 
dry  land,  at  present  occupied  by  the  chalk,  was 
once  at  the  bottom  of  the  sea,  as  we  have  for  any 
matter  of  history  whatever;  while  there  is  no 
justification  for  any  other  belief 

No  less  certain  it  is  that  the  time  during  which 
the  countries  we  now  call  south-east  England, 
France,  Germany,  Poland,  Russia,  Eg}^t,  Arabia, 
Syria,  were  more  or  less  completely  covered  by  a 
deep  sea,  was  of  considerable  duration.  We  have 
already  seen  that  the  chalk  is,  in  places,  more 
than  a  thousand  feet  thick.  I  think  you  will 
agi^ee  with  me,  that  it  must  have  taken  some 
time  for  the  skeletons  of  animalcules  of  a 
hundredth  of  an  inch  in  diameter  to  heap  up 
such  a  mass  as  that.  I  have  said  that  through- 
out the  thickness  of  the  chalk  the  remains  of 
other  animals  are  scattered.  These  remains  are 
often  in  the  most  exquisite  state  of  preservation. 
The  valves  of  the  shell-fishes  are  commonly 
adherent;  the  long  spines  of  some  of  the  sea- 
urchins,  which  would  be  detached  by  the  smallest 
jar,  often  remain  in  their  places.  In  a  word,  it  is 
certain  that  these  animals  have  lived  and  died 


I  ON  A  PIECE   OF   CHALK  21 

when  the  place  which  they  now  occupy  was  the 
surface  of  as  much  of  the  chalk  as  had  then  been 
deposited ;  and  that  each  has  been  covered  up  by 
the  layer  of  Globigcrina  mud,  upon  which  the 
creatures  imbedded  a  little  higher  up  have,  in 
like  manner,  lived  and  died.  But  some  of  these 
remains  prove  the  existence  of  reptiles  of  vast 
size  in  the  chalk  sea.  These  lived  their  time, 
and  had  their  ancestors  and  descendants,  which 
assuredly  implies  time,  reptiles  being  of  slow 
growth. 

There  is  more  curious  evidence,  again,  that  the 
process  of  covering  up,  or,  in  other  words,  the 
deposit  of  Glohigerina  skeletons,  did  not  go  on 
very  fast.  It  is  demonstrable  that  an  animal  of 
the  cretaceous  sea  might  die,  that  its  skeleton 
might  lie  uncovered  upon  the  sea-bottom  long 
enough  to  lose  all  its  outward  coverings  and 
appendages  by  putrefaction ;  and  that,  after  this 
had  happened,  another  animal  might  attach  itself 
to  the  dead  and  naked  skeleton,  might  giow  to 
maturity,  and  might  itself  die  before  the  calcareous 
mud  had  buried  the  whole. 

Cases  of  this  kind  are  admirably  described  by 
Sir  Charles  Lyell.  He  speaks  of  the  frequency 
with  which  geologists  find  in  the  chalk  a  fossilized 
sea-urchin,  to  which  is  attached  the  lower  valve  of 
a  Crania.  This  is  a  kind  of  shell-fish,  with  a  shell 
composed  of  two  pieces,  of  which,  as  in  the  oyster, 
one  is  fixed  and  the  other  free. 


22  ON  A  PIECE   OF  CHALK  i 

"  The  upper  valve  is  almost  invariably  wanting, 
though  occasionally  found  in  a  perfect  state  of 
presei-vation  in  the  white  chalk  at  some  distance. 
In  this  case,  we  see  clearly  that  the  sea-urchin 
first  Hved  from  youth  to  age,  then  died  and  lost 
its  spines,  which  were  carried  away.  Then  the 
young  Crania  adhered  to  the  bared  shell,  grew 
and  perished  in  its  turn ;  after  which,  the  upper 
valve  was  separated  from  the  lower,  before  the 
Echinus  became  enveloped  in  chalky  mud."^ 

A  specimen  in  the  Museum  of  Practical 
Geology,  in  London,  still  further  prolongs  the 
period  which  must  have  elapsed  between  the 
death  of  the  sea-urchin,  and  its  burial  by  the 
Glchigerinm.  For  the  outward  face  of  the  valve 
of  a  Crania,  which  is  attached  to  a  sea-urchin, 
{Micraster),  is  itself  overrun  by  an  incrusting 
coralline,  which  spreads  thence  over  more  or  less 
of  the  surface  of  the  sea-urchin.  It  follows  that, 
after  the  upper  valve  of  the  Crania  fell  off,  the 
surface  of  the  attached  valve  must  have  remained 
exposed  long  enough  to  allow  of  the  growth  of 
the  Avhole  coralline,  since  corallines  do  not  live 
embedded  in  mud.^ 

The  progress  of  knowledge  may,  one  day,  enable 
us  to  deduce  from  such  facts  as  these  the  maxi- 
mum rate  at  which  the  chalk  can  have  ac- 
cumulated, and  thus  to  arrive  at  the  minimum 

1  Elements  of  Geology,  by  Sir  Charles  Lyell,  Bart.  r.E.S., 
p.  23. 


I  ON  A  PIECE   OF  CHALK  23 

duration  of  the  chalk  period.  Suppose  that  the 
valve  of  the  Crania  upon  which  a  coralline  has 
fixed  itself  in  the  way  just  described,  is  so  attached 
to  the  sea-urchin  that  no  part  of  it  is  more  than  an 
inch  above  the  face  upon  which  the  sea-urchin 
rests.  Then,  as  the  coralline  could  not  have  fixed 
itself,  if  the  Crania  had  been  covered  up  with 
chalk  mud,  and  could  not  have  lived  had  itself 
been  so  covered,  it  follows,  that  an  inch  of  chalk 
mud  could  not  have  accumulated  within  the  time 
between  the  death  and  decay  of  the  soft  parts  of 
the  sea-urchin  and  the  growth  of  the  coralline  to 
the  full  size  which  it  has  attained.  If  the  decay 
of  the  soft  parts  of  the  sea-urchin ;  the  attachment, 
growth  to  maturity,  and  decay  of  the  Crania  ;  and 
the  subsequent  attachment  and  growth  of  the 
coralline,  took  a  year  (which  is  a  low  estimate 
enough),  the  accumulation  of  the  inch  of  chalk 
must  have  taken  more  than  a  year:  and  the 
deposit  of  a  thousand  feet  of  chalk  must,  conse- 
quently, have  taken  more  than  twelve  thousand 
years. 

The  foundation  of  all  this  calculation  is,  of 
course,  a  knowledge  of  the  length  of  time  the 
Crania  and  the  coralline  needed  to  attain  their 
full  size ;  and,  on  this  head,  precise  knowledge  is 
at  present  wanting.  But  there  are  circumstances 
which  tend  to  show,  that  nothing  like  an  inch  of 
chalk  has  accumulated  during  the  life  of  a  Crania  ; 
and,  on  any  probable  estimate  of  the  length  of 


24  ON  A  PIECE   OF  CHALK  i 

that  life,  the  chalk  period  must  have  had  a  much 
longer  duration  than  that  thus  roughly  assigned 
to  it. 

Thus,  not  only  is  it  certain  that  the  chalk 
is  the  mud  of  an  ancient  sea-bottom  ;  but  it  is  no 
less  certain,  that  the  chalk  sea  existed  during  an 
extremely  long  period,  though  we  may  not  be 
prepared  to  give  a  precise  estimate  of  the  length 
of  that  period  in  years.  The  relative  duration  is 
clear,  though  the  absolute  duration  may  not  be 
definable.  The  attempt  to  affix  any  precise  date 
to  the  period  at  which  the  chalk  sea  began,  or 
ended,  its  existence,  is  baffled  by  difficulties  of  the 
same  kind.  But  the  relative  age  of  the  cretaceous 
epoch  may  be  determined  with  as  great  ease 
and  certainty  as  the  long  duration  of  that  epoch. 

You  will  have  heard  of  the  interesting  dis- 
coveries recently  made,  in  various  parts  of  Western 
Europe,  of  flint  implements,  obviously  worked  into 
shape  by  human  hands,  under  circumstances  which 
show  conclusively  that  man  is  a  very  ancient 
denizen  of  these  regions.  It  has  been  proved  that 
the  whole  populations  of  Europe,  whose  existence 
has  been  revealed  to  us  in  this  way,  consisted  of 
savages,  such  as  the  Esquimaux  are  now  ;  that,  in 
the  country  which  is  now  France,  they  hunted  the 
reindeer,  and  were  familiar  with  the  ways  of  the 
mammoth  and  the  bison.  The  physical  geography 
of  France  was  in  those  days  different  from  what  it 


I  ON  A  PIECE   OF  CHALK  25 

is  now — the  river  Somme,  for  instance,  having  cut 
its  bed  a  hundred  feet  deeper  between  that  time 
and  this ;  and,  it  is  probable,  that  the  cUmate  was 
more  Hke  that  of  Canada  or  Siberia,  than  that  of 
Western  Europe. 

The  existence  of  these  jDeople  is  forgotten  even 
in  the  traditions  of  the  oldest  historical  nations. 
The  name  and  fame  of  them  had  utterly  vanished 
until  a  few  years  back ;  and  the  amount  of  physical 
change  which  has  been  eifected  since  their  day 
renders  it  more  than  probable  that,  venerable  as 
are  some  of  the  historical  nations,  the  workers  of 
the  chipped  flints  of  Hoxne  or  of  Amiens  are  to 
them,  as  they  are  to  us,  in  point  of  antiquity.  But, 
if  we  assign  to  these  hoar  relics  of  long- vanished 
generations  of  men  the  greatest  age  that  can 
possibly  be  claimed  for  them,  they  are  not  older 
than  the  drift,  or  boulder  clay,  which,  in  com- 
parison with  the  chalk,  is  but  a  very  juvenile 
deposit.  You  need  go  no  further  than  your  own 
sea-board  for  evidence  of  this  fact.  At  one  of  the 
most  charming  spots  on  the  coast  of  Norfolk, 
Cromer,  you  will  see  the  boulder  clay  forming  a 
vast  mass,  which  lies  upon  the  chalk,  and  must 
consequently  have  come  into  existence  after  it. 
Huge  boulders  of  chalk  are,  in  fact,  included  in 
the  clay,  and  have  evidently  been  brought  to  the 
position  they  now  occupy  by  the  same  agency  as 
that  which  has  planted  blocks  of  syenite  from 
Norway  side  by  side  with  them. 


26  ON   A  PIECE   OF   CHALK  i 

The  chalk,  then,  is  certainly  older  than  the 
boulder  clay.  If  you  ask  how  much,  I  will  again 
take  you  no  further  than  the  same  spot  upon  3^our 
own  coasts  for  evidence.  I  have  spoken  of  the 
boulder  clay  and  drift  as  resting  upon  the  chalk. 
That  is  not  strictly  true.  Interposed  between  the 
chalk  and  the  drift  is  a  comparatively  insignifi- 
cant layer,  containing  vegetable  matter.  But  that 
layer  tells  a  wonderful  history.  It  is  full  of  stumps 
of  trees  standing  as  they  grew.  Fir-trees  are  there 
with  their  cones,  and  hazel-bushes  with  their 
nuts ;  there  stand  the  stools  of  oak  and  yew  trees, 
beeches  and  alders.  Hence  this  stratum  is  appro- 
priately called  the  "  forest-bed." 

It  is  obvious  that  the  chalk  must  have  been 
upheaved  and  converted  into  dry  land,  before  the 
timber  trees  could  grow  upon  it.  As  the  bolls  of 
some  of  these  trees  are  from  two  to  three  feet  in 
diameter,  it  is  no  less  clear  that  the  dry  land  thus 
formed  remained  in  the  same  condition  for  long 
ages.  And  not  only  do  the  remains  of  stately 
oaks  and  well-grown  firs  testify  to  the  duration  of 
this  condition  of  things,  but  additional  evidence  to 
the  same  effect  is  afforded  by  the  abundant  re- 
mains of  elephants,  rhinoceroses,  hippopotamuses, 
and  other  great  wild  beasts,  which  it  has  yielded 
to  the  zealous  search  of  such  men  as  the  Rev,  Mr. 
Gunn.  When  you  look  at  such  a  collection  as  he 
has  formed,  and  bethink  you  that  these  elephan- 
tine bones  did  veritably  carry  their  owners  about, 


I  ox   A  PIECE   OF   CHALK  27 

and  these  great  grinders  crunch,  in  the  dark  woods 
of  which  the  forest-bed  is  now  the  only  trace,  it  is 
impossible  not  to  feel  that  they  are  as  good 
evidence  of  the  lapse  of  time  as  the  annual  rings 
of  the  tree  stumps. 

Thus  there  is  a  writing  upon  the  wall  of  cliffs 
at  Cromer,  and  whoso  runs  may  read  it.  It  tells 
us,  with  an  authority  which  cannot  be  impeached, 
that  the  ancient  sea-bed  of  the  chalk  sea  was 
raised  up,  and  remained  dry  land,  until  it  was 
covered  with  forest,  stocked  with  the  great  game  the 
spoils  of  which  have  rejoiced  your  geologists.  How 
long  it  remained  in  that  condition  cannot  be  said ; 
but  "  the  whirligig  of  time  brought  its  revenges  '* 
in  those  days  as  in  these.  That  dry  land,  with 
the  bones  and  teeth  of  generations  of  long-lived 
elephants,  hidden  away  among  the  gnarled  roots 
and  dry  leaves  of  its  ancient  trees,  sank  gradually 
to  the  bottom  of  the  icy  sea,  which  covered  it  with 
huge  masses  of  drift  and  boulder  clay.  Sea-beasts, 
such  as  the  walrus,  now  restricted  to  the  extreme 
north,  paddled  about  where  birds  had  twittered 
among  the  topmost  twigs  of  the  fir-trees.  How 
long  this  state  of  things  endured  we  know  not, 
but  at  length  it  came  to  an  end.  The  upheaved 
glacial  mud  hardened  into  the  soil  of  modern 
Norfolk.  Forests  gi-ew  once  more,  the  wolf  and 
the  beaver  replaced  the  reindeer  and  the  elephant ; 
and  at  length  what  we  call  the  history  of  England 
dawned. 

Thus  you  have,  within  the  limits  of  your  own 


28  ON   A  PIECE   OF   CHALK  I 

county,  proof  that  the  chalk  can  justly  claim  a 
very  much  greater  antiquity  than  even  the  oldest 
physical  traces  of  mankind.  But  we  may  go  fur- 
ther and  demonstrate,  by  evidence  of  the  same 
authority  as  that  which  testifies  to  the  existence 
of  the  father  of  men,  that  the  chalk  is  vastly  older 
than  Adam  himself  The  Book  of  Genesis  informs 
us  that  Adam,  immediately  upon  his  creation,  and 
before  the  aj^pearance  of  Eve,  was  placed  in  the 
Garden  of  Eden.  The  problem  of  the  geographical 
position  of  Eden  has  greatly  vexed  the  spirits  of 
the  learned  in  such  matters,  but  there  is  one 
point  respecting  which,  so  far  as  I  know,  no  com- 
mentator has  ever  raised  a  doubt.  This  is,  that 
of  the  four  rivers  which  are  said  to  run  out  of  it, 
Euphrates  and  Hiddekel  are  identical  with  the 
livers  now  known  by  the  names  of  Euphrates  and 
Tigris.  But  the  whole  country  in  which  these 
mighty  rivers  take  their  origin,  and  through 
which  they  run,  is  composed  of  rocks  which  are 
either  of  the  same  age  as  the  chalk,  or  of  later 
date.  So  that  the  chalk  must  not  only  have  been 
formed,  but,  after  its  formation,  the  time  required 
for  the  deposit  of  these  later  rocks,  and  for  their 
upheaval  into  dry  land,  must  have  elapsed,  before 
the  smallest  brook  which  feeds  the  swift  stream 
of  "  the  great  river,  the  river  of  Babylon,"  began 
to  flow. 

Thus,  evidence  which  cannot  be  rebutted,  and 
which  need  not  be  strengthened,  though  if  time 


I  ON  A  PIECE   OF   CHALK  29 

permitted  I  might  indefinitely  increase  its  quantity, 
compels  you  to  believe  that  the  earth,  from  the 
time  of  the  chalk  to  the  present  day,  has  been  the 
theatre  of  a  series  of  changes  as  vast  in  their 
amount,  as  they  were  slow  in  their  progress.  The 
area  on  which  we  stand  has  been  first  sea  and 
then  land,  for  at  least  four  alternations ;  and  has 
remained  in  each  of  these  conditions  for  a  period 
of  great  length. 

Nor  have  these  wonderful  metamorphoses  of  sea 
into  land,  and  of  land  into  sea,  been  confined  to  one 
corner  of  England.  During  the  chalk  period,  or 
"  cretaceous  epoch,"  not  one  of  the  present  great 
physical  features  of  the  globe  was  in  existence. 
Our  great  mountain  ranges,  Pyrenees,  Alps, 
Himalayas,  Andes,  have  all  been  upheaved  since 
the  chalk  was  deposited,  and  the  cretaceous  sea 
flowed  over  the  sites  of  Sinai  and  Ararat.  All 
this  is  certain,  because  rocks  of  cretaceous,  or  still 
later,  date  have  shared  in  the  elevatory  movements 
which  gave  rise  to  these  mountain  chains;  and 
may  be  found  perched  up,  in  some  cases,  many 
thousand  feet  high  upon  their  flanks.  And  evi- 
dence of  equal  cogency  demonstrates  that,  though, 
in  Norfolk,  the  forest-bed  rests  directly  upon  the 
chalk,  yet  it  does  so,  not  because  the  period  at 
which  the  forest  grew  immediately  followed  that 
at  which  the  chalk  was  formed,  but  because  an 
immense  lapse  of  time,  represented  elsewhere  by 
thousands  of  feet  of  rock,  is  not  indicated  at  Cromer 


so  ON   A  PIECE   OF   CHALK  1 

I  must  ask  you  to  believe  that  there  is  no  less 
conclusive  proof  that  a  still  more  prolonged  suc- 
cession of  similar  changes  occurred,  before  the 
chalk  was  deposited.  Nor  have  we  any  reason  to 
think  that  the  first  term  in  the  series  of  these 
changes  is  known.  The  oldest  sea-beds  preserved 
to  us  are  sands,  and  mud,  and  pebbles,  the  wear 
and  tear  of  rocks  which  were  formed  in  still  older 
oceans. 

But,*  great  as  is  the  magnitude  of  these  physical 
changes  of  the  world,  they  have  been  accompanied 
by  a  no  less  striking  series  of  modifications  in  its 
living  inhabitants.  All  the  great  classes  of 
animals,  beasts  of  the  field,  fowls  of  the  air, 
creeping  things,  and  things  which  dwell  iq  the 
waters,  flourished  upon  the  globe  long  ages  before 
the  chalk  was  deposited.  Very  few,  however,  if 
any,  of  these  ancient  forms  of  animal  life  were 
identical  with  those  which  now  Kve.  Certainly 
not  one  of  the  higher  animals  was  of  the  same 
species  as  any  of  those  now  in  existence.  The 
beasts  of  the  field,  in  the  da3's  before  the  chalk, 
were  not  our  beasts  of  the  field,  nor  the  fowls  of 
the  air  such  as  those  which  the  eye  of  men  has 
seen  flying,  unless  his  antiquity  dates  infinitely 
further  back  than  we  at  present  surmise.  If  we 
could  be  carried  back  into  those  times,  we  should 
be  as  one  suddenly  set  down  in  AustraHa  before  it 
was  colonized.  We  should  see  mammals,  birds, 
reptiles,  fishes,  insects,  snails,  and  the  like,  clearly 


r  ON    A  PIECE   OF   CHALK  81 

recognizable  as  such,  and  yet  not  one  of  them 
would  be  just  the  same  as  those  with  which  we 
are  familiar,  and  many  would  be  extremely 
different. 

From  that  time  to  the  present,  the  population 
of  the  world  has  undergone  slow  and  gradual,  but 
incessant,  changes.  There  has  been  no  grand 
catastrophe — no  destroyer  has  swept  away  the 
forms  of  life  of  one  period,  and  replaced  them  by 
a  totally  new  creation :  but  one  species  has 
vanished  and  another  has  taken  its  place ; 
creatures  of  one  tjrpe  of  structure  have  diminished, 
those  of  another  have  increased,  as  time  has 
passed  on.  And  thus,  while  the  differences  be- 
tween the  living  creatures  of  the  time  before  the 
chalk  and  those  of  the  present  day  appear 
startling,  if  placed  side  by  side,  we  are  led  from 
one  to  the  other  by  the  most  gradual  progress,  if 
we  follow  the  course  of  Nature  through  the 
whole  series  of  those  relics  of  her  operations  which 
she  has  left  behind.  It  is  by  the  population  of 
the  chalk  sea  that  the  ancient  and  the  modem 
inhabitants  of  the  world  are  most  completely  con- 
nected. The  groups  which  are  d3dng  out  flourish, 
side  by  side,  with  the  groups  which  are  now  the 
dominant  forms  of  Hfe.  Thus  the  chalk  contains 
remains  of  those  strange  flying  and  swimming 
reptiles,  the  pterodactyl,  the  ichthyosaurus,  and 
the  plesiosaurus,  which  are  found  in  no  later 
deposits,  but  abounded  in  preceding  ages.      The 


32  ON   A  PIECE   OF   CHALK  I 

chambered  shells  called  ammonites  and  belemnites, 
which   are    so  characteristic  of  the  period   pre- 
ceding the  cretaceous,  in  like  manner  die  with  it. 
But,  amongst    these    fading   remainders    of  a 
previous  state  of  things,  are  some   very  modem 
forms  of  life,  looking  like  Yankee  pedlars  among 
a  tribe  of  Red   Indians.      Crocodiles  of  modem 
type    appear;    bony  fishes,  many  of  them   very 
similar   to  existing  species,  almost  supplant  the 
forms  of  fish  which  predominate  in  more  ancient 
seas;    and  many  kinds    of  living   shell-fish  first 
become  known  to  us  in  the  chalk.    The  vegetation 
acquires  a  modern  aspect.      A  few  living  animals 
are  not  even  distinguishable  as  species,  from  those 
which  existed  at  that  remote  epoch.     The  Glchi- 
gerina  of  the  present   day,   for   example,  is   not 
different  specifically  from  that  of  the  chalk ;  and 
the  same  may  be  said  of  many  other  Foraminifera. 
I  think  it  probable  that  critical  and  unprejudiced 
examination  will  show  that  more  than  one  species 
of  much  higher  animals  have  had  a  similar  lon- 
gevity;  but   the   only  example   which   I  can  at 
present  give  confidently  is  the  snake's-head  lamp- 
shell  {Terehrahdina  caput  serpentis),  which  lives  in 
our  English  seas  and  abounded  (as  Tcrehratulina 
striata  of  authors)  in  the  chalk. 

The  longest  line  of  human  ancestry  must  hide 
its  diminished  head  before  the  pedigree  of  this 
insignificant  shell-fish.  We  Englishmen  are  proud 
to   have   an   ancestor   who   was   present   at   the 


I  ON  A  PIECE   OF   CHALK  33 

Battle  of  Hastings.  The  ancestors  of  Tcrebratulina 
caput  serpentis  may  have  been  present  at  a  battle 
of  Ichthyosauria  in  that  part  of  the  sea  which, 
when  the  chalk  was  forming,  flowed  over  the  site 
of  Hastings.  While  all  around  has  changed,  this 
Terehratulina  has  peacefully  propagated  its  species 
from  generation  to  generation,  and  stands  to  this 
day,  as  a  living  testimony  to  the  continuity  of  the 
present  with  the  past  history  of  the  globe. 

Up  to  this  moment  I  have  stated,  so  far  as  I 
know,  nothing  but  well-authenticated  facts,  and 
the  immediate  conclusions  which  they  force  upon 
the  mind.  But  the  mind  is  so  constituted  that  it 
does  not  willingly  rest  in  facts  and  immediate 
causes,  but  seeks  always  after  a  knowledge  of  the 
remoter  links  in  the  chain  of  causation. 

Taking  the  many  changes  of  any  given  spot  of 
the  earth's  surface,  from  sea  to  land  and  from  land 
to  sea,  as  an  established  fact,  we  cannot  refrain 
from  asking  ourselves  how  these  changes  have 
occurred.  And  when  we  have  explained  them — 
as  they  must  be  explained — by  the  alternate  slow 
movements  of  elevation  and  depression  which 
have  affected  the  crust  of  the  earth,  we  go  still 
further  back,  and  ask.  Why  these  movements  ? 

I  am  not  certain  that  any  one  can  give  you  a 
satisfactory  answer  to  that  question.  Assuredly  I 
cannot.  All  that  can  be  said,  for  certain,  is,  that 
such  movements  are  part  of  the  ordinary  course 

189 


34  ON  A  PIECE   OF  CHALK  T 

of  nature,  inasmuch  as  they  are  going  on  at  the 
present  time.  Direct  proof  may  be  given,  that 
some  parts  of  the  land  of  the  northern  hemisphere 
are  at  this  moment  insensibly  rising  and  others 
insensibly  sinking ;  and  there  is  indirect,  but  per- 
fectly satisfactory,  proof,  that  an  enormous  area 
now  covered  by  the  Pacific  has  been  deepened 
thousands  of  feet,  since  the  present  inhabitants  of 
that  sea  came  into  existence.  Thus  there  is  not 
a  shadow  of  a  reason  for  believing  that  the 
physical  changes  of  the  globe,  in  past  times,  have 
been  effected  by  other  than  natural  causes.  Is 
there  any  more  reason  for  beHeving  that  the  con- 
comitant modifications  in  the  forms  of  the  living 
inhabitants  of  the  globe  have  been  brought  about 
in  other  ways  ? 

Before  attempting  to  answer  this  question,  let 
us  try  to  form  a  distinct  mental  picture  of  what 
has  happened  in  some  special  case.  The  crocodiles 
are  animals  which,  as  a  group,  have  a  very  vast 
antiquity.  They  abounded  ages  before  the  chalk 
was  deposited ;  they  throng  the  rivers  in  warm 
climates,  at  the  present  day.  There  is  a  difference 
in  the  form  of  the  joints  of  the  back-bone,  and  in 
some  minor  particulars,  between  the  crocodiles  of 
the  present  epoch  and  those  which  lived  before 
the  chalk  ;  but,  in  the  cretaceous  epoch,  as  I  have 
already  mentioned,  the  crocodiles  had  assumed 
the  modern  t}^e  of  structure.  Notwithstand- 
ing  this,  the  crocodiles  of    the    chalk    are    not 


I  ON  A  PIECE   OF   CHALK  35 

identically  the  same  as  those  which  lived  in  the 
times  called  "  older  tertiary,"  which  succeeded  the 
cretaceous  epoch  ;  and  the  crocodiles  of  the  older 
tertiaries  are  not  identical  with  those  of  the 
newer  tertiaries,  nor  are  these  identical  with 
existing  forms.  I  leave  open  the  question  whether 
particular  species  may  have  lived  on  from  epoch 
to  epoch.  But  each  epoch  has  had  its  peculiar 
crocodiles;  though  all,  since  the  chalk,  have 
belonged  to  the  modern  t}'pe,  and  differ  simply  in 
their  proportions,  and  in  such  structural  particulars 
as  are  discernible  only  to  trained  eyes. 

How  is  the  existence  of  this  long  succession  of 
different  species  of  crocodiles  to  be  accounted  for  ? 
Only  two  suppositions  seem  to  be  open  to  us — 
Either  each  species  of  crocodile  has  been  specially 
created,  or  it  has  arisen  out  of  some  pre-existing 
form  by  the  operation  of  natural  causes.  Choose 
your  hypothesis ;  I  have  chosen  mine.  I  can  find 
no  warranty  for  believing  in  the  distinct  creation 
of  a  score  of  successive  species  of  crocodiles  in  the 
course  of  countless  ages  of  time.  Science  gives 
no  countenance  to  such  a  wild  fancy ;  nor  can 
even  the  perverse  ingenuity  of  a  commentator 
pretend  to  discover  this  sense,  in  the  simple  words 
in  which  the  writer  of  Genesis  records  the  pro- 
ceedings of  the  fifth  and  six  days  of  the  Creation. 

On  the  other  hand,  I  see  no  good  reason  for 
doubting  the  necessary  alternative,  that  all  these 
varied  species  have  been  evolved  from  pre-existing 


36  ON   A  PIECE   OF   CHALK  I 

crocodilian  forms,  by  tlie  operation  of  causes  as 
completely  a  part  of  the  common  order  of  nature 
as  those  which  have  efifected  the  changes  of  the 
inorganic  world.  Few  will  venture  to  affirm  that 
the  reasoning  which  applies  to  crocodiles  loses  its 
force  among  other  animals,  or  among  plants.  If 
one  series  of  species  has  come  into  existence  by 
the  operation  of  natural  causes,  it  seems  folly  to 
deny  that  all  may  have  arisen  in  the  same  way. 

A  small  beginning  has  led  us  to  a  great  ending. 
If  I  were  to  put  the  bit  of  chalk  with  which  we 
started  into  the  hot  but  obscure  flame  of  burning 
hydrogen,  it  would  presently  shine  Hke  the  sun. 
It  seems  to  me  that  this  physical  metamorphosis 
is  no  false  image  of  what  has  been  the  result  of 
our  subjecting  it  to  a  jet  of  fervent,  though  no- 
wise brilliant,  thought  to-night.  It  has  become 
luminous,  and  its  clear  rays,  penetrating  the  abyss 
of  the  remote  past,  have  brought  within  our  ken 
some  stages  of  the  evolution  of  the  earth.  And 
in  the  shifting  "  without  haste,  but  without  rest " 
of  the  land  and  sea,  as  in  the  endless  variation  of 
the  forms  assumed  by  living  beings,  we  have 
observed  nothing  but  the  natural  product  of  the 
forces  originally  possessed  by  the  substance  of  the 
universe. 


n 

THE  PROBLEMS  OF  THE  DEEP  SEA 

[1873] 

ONthe21stofDecember,1872,H.M.S.(7^6fZ/e7i(7^r,an 
eighteen  gun  corvette,  of  2,000  tons  burden,  sailed 
from  Portsmouth  harbour  for  a  three,  or  perhaps  four, 
years'  cruise.  No  man-of-war  ever  left  that  famous 
port  before  with  so  singular  an  equipment.  Two  of 
the  eighteen  sixty-eight  pounders  of  the  Chcdlengers 
armament  remained  to  enable  her  to  speak  with 
effect  to  sea-rovers,  haply  devoid  of  any  respect 
for  science,  in  the  remote  seas  for  which  she  is 
bound  ;  but  the  main-deck  was,  for  the  most  part, 
stripped  of  its  war-like  gear,  and  fitted  up  with 
physical,  chemical,  and  biological  laboratories; 
photography  had  its  dark  cabin ;  while  apparatus 
for  dredging,  trawling,  and  sounding ;  for  photo- 
meters and  for  thermometers,  filled  the  space 
formerly  occupied  by  guns  and  gun-tackle,  pistols 
and  cutlasses. 


38     THE  PROBLEMS  OF  THE  DEEP  SEA      n 

The  crew  of  the  Challenger  match  her  fittings. 
Captain  Nares,  his  officers  and  men,  are  ready  to 
look  after  the  interests  of  hydrography,  work  the 
ship,  and,  if  need  be,  fight  her  as  seamen  should ; 
while  there  is  a  staff  of  scientific  civilians,  under 
the  general  direction  of  Dr.  Wjrvdlle  Thomson, 
F.R.S.  (Professor  of  Natural  History  in  Edinbm^gh 
University  by  rights,  but  at  present  detached  for 
duty  in  partihcs),  whose  business  it  is  to  turn  all 
the  wonderfully  packed  stores  of  appliances  to 
account,  and  to  accumulate,  before  the  ship  returns 
to  England,  such  additions  to  natural  knowledge 
as  shall  justify  the  labour  and  cost  involved  in  the 
fitting  out  and  maintenance  of  the  expedition. 

Under  the  able  and  zealous  superintendence  of 
the  Hydrographer,  Admiral  Richards,  every  pre- 
caution which  experience  and  forethought  could 
devise  has  been  taken  to  provide  the  expedition 
with  the  material  conditions  of  success;  and  it 
would  seem  as  if  nothing  short  of  wreck  or  pesti- 
lence, both  most  improbable  contingencies,  could 
prevent  the  Challenger  from  doing  splendid  work, 
and  opening  up  a  new  era  in  the  history  of  scien- 
tific voyages. 

The  dispatch  of  this  expedition  is  the  culmina- 
tion of  a  series  of  such  enterprises,  gradually  in- 
creasing in  magnitude  and  importance,  which  the 
Admiralty,  greatly  to  its  credit,  has  carried  out  for 
some  years  past ;  and  the  history  of  which  is  given 
by  Dr.  Wyrille  Thomson  in  the  beautifully  illus- 


n      THE  PROBLEMS  OF  THE  DEEP  SEA     39 

trated  volume  entitled  "  The  Depths  of  the  Sea," 
published  since  his  departure. 

"  In  the  spring  of  the  year  1868.  my  friend  Dr.  W.  B.  Car- 
penter, at  that  time  one  of  the  Vice-Presidents  of  the  Royal 
Society,  was  with  me  in  Ireland,  where  we  were  working  out 
together  the  structure  and  development  of  the  Crinoids.  I  had 
long  previously  had  a  profound  conviction  that  the  land  of 
promise  for  the  naturalist,  the  only  remaining  region  where 
there  were  endless  novelties  of  extraordinary  interest  ready  to 
the  hand  which  had  the  means  of  gathering  them,  was  the 
bottom  of  the  deep  sea.  I  had  even  had  a  glimpse  of  some  of 
these  treasures,  for  I  had  seen,  the  year  before,  with  Prof.  Sars, 
the  forms  which  I  have  already  mentioned  dredged  by  his  son 
at  a  depth  of  300  to  400  fathoms  off  the  Loffoten  Islands.  I 
propounded  my  views  to  my  fellow-labourer,  and  we  discussed 
the  subject  many  times  over  our  microscojies.  I  strongly  urged 
Dr.  Carpenter  to  use  his  influence  at  head-quarters  to  induce  the 
Admiralty,  probably  through  the  Council  of  the  Royal  Society, 
to  give  us  the  use  of  a  vessel  properly  fitted  with  dredging  gear 
and  all  necessary  scientific  apparatus,  that  many  heavy  questions 
as  to  the  state  of  things  in  the  depths  of  the  ocean,  which  were 
still  in  a  state  of  uncertainty,  might  be  definitely  settled. 
After  full  consideration,  Dr.  Carpenter  ])romised  his  hearty  co- 
operation, and  we  agreed  that  I  should  write  to  him  on  his 
return  to  London,  indicating  generally  the  results  which  I  an- 
ticipated, and  sketching  out  what  I  conceived  to  be  a  promising 
line  of  inquiry.  The  Council  of  the  Royal  Society  warmly 
supported  the  proposal ;  and  I  give  here  in  chronological  order 
the  short  and  eminently  satisfactory  correspondence  which  led 
to  the  Admiralty  placing  at  the  disposal  of  Dr.  Carpenter  and 
myself  the  gunboat  Lightning,  under  the  command  of  Staff- 
Comraauder  May,  R  N.,  in  the  summer  of  1868,  for  a  trial 
cruise  to  the  North  of  Scotland,  and  afterwards  to  the  much 
wider  surveys  in  H.M.S.  Porcupine,  Captain  Calver,  R.N., 
which  were  made  with  the  additional  association  of  Mr.  Gwyu 
Jeffreys,  in  the  summers  of  the  years  1869  and  1870."  ^ 

1  The  Depths  of  the  Sea,  pp.  49-50. 


40     THE  PROBLEMS  OF  THE  DEEP  SEA      ii 

Plain  men  may  be  puzzled  to  understand  why 
Dr.  Wyville  Thomson,  not  bemg  a  cynic,  should 
relegate  the  "  Land  of  Promise  "  to  the  bottom  of 
the  deep  sea :  they  may  still  more  wonder  what 
manner  of  "  milk  and  honey "  the  Challenger 
expects  to  find ;  and  their  perplexity  may  Avell 
rise  to  its  maximum,  when  they  seek  to  divine  the 
manner  in  which  that  milk  and  honey  are  to  be 
got  out  of  so  inaccessible  a  Canaan.  I  will,  there- 
fore, endeavour  to  give  some  answer  to  these 
questions  in  an  order  the  reverse  of  that  in  which 
I  have  stated  them. 

Apart  from  hooks,  and  lines,  and  ordinary  nets, 
fishermen  have,  from  time  immemorial,  made  use 
of  two  kinds  of  implements  for  getting  at  sea- 
creatures  which  live  beyond  tide-marks — these  are 
the  "  dreds^e  "  and  the  "  trawl."  The  dredo-e  is 
used  by  oyster-fishermen.  Imagine  a  large  bag, 
the  mouth  of  which  has  the  shape  of  an  elongated 
parallelogram,  and  is  fastened  to  an  iron  frame  of 
the  same  shape,  the  two  long  sides  of  this  rim 
being  fashioned  into  scrapers.  Chains  attach  the 
ends  of  the  frame  to  a  stout  rope,  so  that  when 
the  bag  is  dragged  along  by  the  rope  the  edge  of  one 
of  the  scrapers  rests  on  the  ground,  and  scrapes 
whatever  it  touches  into  the  bag.  The  oyster- 
dredger  takes  one  of  these  machines  in  his  boat, 
and  when  he  has  reached  the  oyster-bed  the 
dredge  is  tossed  overboard  ;  as  soon  as  it  has  sunk 
to  the  bottom  the  rope  is  paid  out  sufficiently 


It      THE  PROBLEMS  OF  THE  DEEP  SEA     41 

to  prevent  it  from  pulling  the  dredge  directly 
upwards,  and  is  then  made  fast  while  the  boat 
goes  ahead.  The  dredge  is  thus  dragged  along 
and  scrapes  oysters  and  other  sea-animals  and 
plants,  stones,  and  mud  into  the  bag.  When  the 
dredger  judges  it  to  be  full  he  hauls  it  up,  picks 
out  the  oysters,  throws  the  rest  overboard,  and 
begins  again. 

Dredging  in  shallow  water,  say  ten  to  twenty 
fathoms,  is  an  easy  operation  enough  ;  but  the 
deeper  the  dredger  goes,  the  heavier  must  be  his 
vessel,  and  the  stouter  his  tackle,  while  the  opera- 
tion of  hauling  up  becomes  more  and  more 
laborious.  Dredging  in  150  fathoms  is  very  hard 
work,  if  it  has  to  be  carried  on  by  manual  labour ; 
but  by  the  use  of  the  donkey-engine  to  supply 
power,^  and  of  the  contrivances  kno\vn  as  "  accumu- 
lators," to  diminish  the  risk  of  snapping  the  dredge 
rope  by  the  rolling  and  pitching  of  the  vessel,  the 
dredge  has  been  worked  deeper  and  deeper,  until 
at  last,  on  the  22nd  of  July,  1869,  H.M.S.  Pormpine 
being  in  the  Bay  of  Biscay,  Captain  Calver,  her 
commander,  performed  the  unprecedented  feat  of 
dredging  in  2,435  fathoms,  or  14,610  feet,  a  depth 

^  The  emotional  side  of  the  scientific  nature  has  its  singulari- 
ties. Many  persons  will  call  to  mind  a  certain  philosopher's 
tenderness  over  his  watch — "the  little  creature" — which  was 
so  singularly  lost  and  found  again.  But  Dr.  Wyville  Thomson 
surpasses  the  owner  of  the  watch  in  his  loving-kindness  towards 
a  donkey-engine.  "This  little  engine  was  the  comfort  of  our 
lives.  Once  or  twice  it  was  overstrained,  and  then  we  pitied  tho 
Willing  little  thing,  panting  like  an  overtaxed  horse." 


42     THE  PROBLEMS  OF  THE  DEEP  SEA      n 

nearly  equal  to  the  height  of  Mont  Blanc.  The 
dredge  "  was  rapidly  hauled  on  deck  at  one  o'clock 
in  the  morning  of  the  23rd,  after  an  absence  of 
7i  hours,  and  a  journey  of  upwards  of  eight  statute 
miles,"  with  a  hundred  weight  and  a  half  of  solid 
contents. 

The  trawl  is  a  sort  of  net  for  catching  those  fish 
which  habitually  live  at  the  bottom  of  the  sea, 
such  as  soles,  plaice,  turbot,  and  gurnett.  The 
mouth  of  the  net  may  be  thirty  or  forty  feet  wide, 
and  one  edge  of  its  mouth  is  fastened  to  a  beam 
of  wood  of  the  same  length.  The  two  ends  of  the 
beam  are  supported  by  curved  pieces  of  iron, 
which  raise  the  beam  and  the  edge  of  the  net 
which  is  fastened  to  it,  for  a  short  distance,  while 
the  other  edge  of  the  mouth  of  the  net  trails  upon 
the  ground.  The  closed  end  of  the  net  has  the 
form  of  a  great  pouch;  and,  as  the  beam  is 
dragged  along,  the  fish,  roused  from  the  bottom 
by  the  sweeping  of  the  net,  readily  pass  into  its 
mouth  and  accumulate  in  the  pouch  at  its  end. 
After  drifting  with  the  tide  for  six  or  seven  hours 
the  trawl  is  hauled  up,  the  marketable  fish  are 
picked  out,  the  others  thrown  away,  and  the  trawl 
sent  overboard  for  another  operation. 

More  than  a  thousand  sail  of  well-found  trawlers 
are  constantly  engaged  in  sweeping  the  seas 
around  our  coast  in  this  way,  and  it  is  to  them 
that  we  owe  a  very  large  proportion  of  our  supply 
of  fish.     The  difficulty  of  trawhng,  like  that  of 


II      THE  PROBLEMS  OF  THE  DEEP  SEA     43 

dredging,  rapidly  increases  with  the  depth  at 
which  the  operation  is  performed ;  and,  until  the 
other  day,  it  is  probable  that  trawling  at  so  great 
d  depth  as  100  fathoms  was  something  unheard  of. 
But  the  first  news  from  the  Challenger  opens  up 
new  possibilities  for  the  traAvl. 

Dr.  W3rviUe  Thomson  writes  ("  Nature,"  March 
20,  1873)  :— 

"For  the  first  two  or  three  hauls  in  very  deep  water  off  the 
coast  of  Portugal,  the  dredge  came  up  filled  with  the  usual 
'Atlantic  ooze,'  tenacious  and  uniform  throughout,  and  the 
work  of  hours,  in  sifting,  gave  the  very  smallest  possible  result. 
We  were  extremely  anxious  to  get  some  idea  of  the  general 
character  of  the  Fauna,  and  particularly  of  the  distribution  of 
the  higher  groups  ;  and  after  various  suggestions  for  modification 
of  the  dredge,  it  was  proposed  to  try  the  ordinary  trawl.  We 
had  a  compact  trawl,  with  a  15-feet  beam,  on  Iward,  and  we 
sent  it  down  off  Cape  St.  Vincent  at  a  depth  of  600  fathoms. 
The  experiment  looked  hazardous,  but,  to  our  great  satisfaction, 
the  trawl  came  up  all  right  and  contained,  with  many  of  the 
larger  invertebrata,  several  fishes,  .  .  .  After  the  first  attempt 
we  tried  the  trawl  several  times  at  depths  of  1090,  1525,  and, 
finally,  2125  fathoms,  and  always  with  success," 

To  the  coral-fishers  of  the  Mediterranean,  who 
seek  the  precious  red  coral,  which  grows  firmly 
fixed  to  rocks  at  a  depth  of  sixty  to  eighty 
fathoms,  both  the  dredge  and  the  trawl  would  be 
useless.  They,  therefore,  have  recourse  to  a  sort 
of  frame,  to  which  are  fastened  long  bundles  of 
loosely  netted  hempen  cord,  and  which  is  lowered 
by  a  rope  to  the  depth  at  which  the  hempen  cords 
can  sweep  over  the  surface  of  the  rocks  and  break 


44     THE  PROBLEMS  OF  THE  DEEP  SEA 


II 


off  the  coral,  which  is  brought  up  entangled  in  the 
cords.  A  similar  contrivance  has  arisen  out  of  the 
necessities  of  deep-sea  exploration. 

In  the  course  of  the  dredging  of  the  Forcupine, 
it  was  frequently  found  that,  while  few  objects  of 
interest  were  brought  up  within  the  dredge,  many 
living  creatures  came  up  sticking  to  the  outside  of 
the  dredge-bag,  and  even  to  the  fii^t  few  fathoms 
of  the  dredge-rope.  The  mouth  of  the  dredge 
doubtless  rapidly  filled  with  mud,  and  thus  the 
things  it  should  have  brought  up  were  shut  out. 
To  remedy  this  inconvenience  Captain  Calver 
devised  an  arrangement  not  unlike  that  employed 
by  the  coral-fishers.  He  fastened  half  a  dozen 
swabs,  such  as  are  used  for  drying  decks,  to  the 
dredge.  A  swab  is  something  like  what  a  birch- 
broom  would  be  if  its  twigs  were  made  of  long, 
coarse,  hempen  yarns.  These  dragged  along  after 
the  dredge  over  the  surface  of  the  mud,  and  en- 
tangled the  creatures  living  there — multitudes  of 
which,  twisted  up  in  the  strands  of  the  swabs, 
were  brought  to  the  surface  with  the  dredge.  A 
ftirther  improvement  was  made  by  attaching  a 
long  iron  bar  to  the  bottom  of  the  dredge  bag,  and 
fastening  large  bunches  of  teased-out  hemp  to  the 
end  of  this  bar.  These  "  tangles "  bring  up 
immense  quantities  of  such  animals  as  have  long 
arms,  or  spines,  or  prominences  which  readily 
become  caught  in  the  hemp,  but  they  are  very 
destructive  to  the  fragile  organisms  which  they 


n      THE  PROBLEMS  OF  THE  DEEP  SEA     45 

imprison  ;  and,  now  that  the  trawl  can  be  success- 
fully worked  at  the  greatest  depths,  it  may  be 
expected  to  supersede  them  ;  at  least,  wherever 
the  ground  is  soft  enough  to  permit  of  trawling. 

It  is  obvious  that  between  the  dredge,  the  trawl, 
and  the  tangles,  there  is  little  chance  for  any 
organism,  except  such  as  are  able  to  burrow 
rapidly,  to  remain  safely  at  the  bottom  of  any  part 
of  the  sea  which  the  ChcdlengeT  undertakes  to 
explore.  And,  for  the  first  time  in  the  history  of 
scientific  exploration,  we  have  a  fair  chance  of  learn- 
ing what  the  population  of  the  depths  of  the  sea  is 
like  in  the  most  widely  different  parts  of  the  world. 

And  now  arises  the  next  question.  The  means 
of  exploration  being  fairly  adequate,  what  forms 
of  life  may  be  looked  for  at  these  vast  depths  ? 

The  systematic  study  of  the  Distribution  of 
living  beings  is  the  most  modern  branch  of  Biolo- 
gical Science,  and  came  into  existence  long  after 
Morphology  and  Physiology  had  attained  a  con- 
siderable development.  This  naturally  does  not 
imply  that,  from  the  time  men  began  to  observe 
natural  phenomena,  they  were  ignorant  of  the  fact 
that  the  animals  and  plants  of  one  part  of  the 
world  are  different  from  those  in  other  regions ;  or 
that  those  of  the  hills  are  different  from  those  of 
the  plains  in  the  same  region;  or  finally  that 
some  marine  creatures  are  found  only  in  the 
shallows,  while  others  inhabit  the  deeps.  Never- 
theless, it  was  only  after  the  discovery  of  America 


46  THE   PROBLEMS   OF   THE  DEEP  SEA  n 

that  tli8  attention  of  naturalists  was  powerfully 
drawn  to  the  wonderful  differences  between  the 
animal  population  of  the  central  and  southern 
parts  of  the  new  world  and  that  of  those  parts  of 
the  old  world  which  lie  under  the  same  parallels  of 
latitude.  So  far  back  as  1667  Abraham  Mylius, 
in  his  treatise  "  De  Animalium  origine  et  migratione 
poj)ulorum,"  argues  that,  since  there  are  innumer- 
able species  of  animals  in  America  which  do  not 
exist  elsewhere,  they  must  have  been  made  and 
placed  there  by  the  Deity :  Buffon  no  less  forcibly 
insists  upon  the  difference  between  the  FaunoB  of 
the  old  and  new  world.  But  the  first  attempt  to 
gather  facts  of  this  order  into  a  whole,  and  to  co- 
ordinate them  into  a  series  of  generalizations,  or 
laws  of  Geogi^aphical  Distribution,  is  not  a  century 
old,  and  is  contained  in  the  "  Specimen  Zoologic? 
Geographicoe  Quadrupedum  Domicilia  et  Migra- 
tiones  sistens,"  published,  in  1777,  by  the  learned 
Brunswick  Professor,  Eberhard  Zimmermann,  who 
illustrates  his  work  by  what  he  calls  a  "  Tabula 
Zoographica,"  which  is  the  oldest  distributional 
map  known  to  me. 

In  regard  to  matters  of  fact,  Zimmermann's 
chief  aim  is  to  show  that  among  terrestrial 
mammals,  some  occur  all  over  the  world,  while 
others  are  restricted  to  .particular  areas  of  gi^eater 
or  smaller  extent ;  and  that  the  abundance  of 
species  follows  temperature,  being  greatest  in  warm 
and  least  in  cold  climates.      But  marine  animals 


II  THE   PROBLEMS   OF   THE   DEEP   SEA  47 

he  thinks,  obey  no  such  law.  The  Arctic  and 
Atlantic  seas,  he  says,  are  as  full  of  fishes  and 
other  animals  as  those  of  the  tropics.  It  is,  there- 
fore, clear  that  cold  does  not  affect  the  dwellers 
in  the  sea  as  it  does  land  animals,  and  that  this 
must  be  the  case  follows  from  the  fact  that  sea 
water,  "propter  varias  quas  continet  bituminis 
spiritusque  particulas,"  freezes  with  much  more 
difficulty  than  fresh  water.  On  the  other  hand, 
the  heat  of  the  Equatorial  sun  penetrates  but  a 
short  distance  below  the  surface  of  the  ocean. 
Moreover,  according  to  Zimmermann,  the  incessant 
disturbance  of  the  mass  of  the  sea  by  winds  and 
tides,  so  mixes  up  the  warm  and  the  cold  that 
life  is  evenly  diffused  and  abundant  throughout 
the  ocean. 

In  1810,  Risso,  in  his  work  on  the  Ichthyology 
of  Nice,  laid  the  foundation  of  what  has  since  been 
termed  "  bath}Txietrical "  distribution,  or  distribu- 
tion in  depth,  by  showing  that  regions  of  the  sea 
bottom  of  different  depths  could  be  distinguished 
by  the  fishes  which  inhabit  them.  There  was  the 
littoral  region  between  tide  marks  with  its  sand- 
eels,  pipe  fishes,  and  blennies :  the  scaivced  region, 
extending  from  lowwater-mark  to  a  depth  of  450 
feet,  with  its  wrasses,  rays,  and  flat  fish ;  and  the 
deep-sea  region,  fi:om  450  feet  to  1500  feet  or  more, 
with  its  file-fish,  sharks,  gurnards,  cod,  and  sword- 
fish. 

More  than  twenty  years  later,  MM.  Audouin  and 


48     THE  PROBLEMS  OF  THE  DEEP  SEA      n 

Milne  Edwards  carried  out  the  principle  of  distin- 
guishing the  FaunsG  of  different  zones  of  depth 
much  more  minutely,  in  their  "  Recherches  pour 
servir  a  I'Histoire  Naturelle  du  Littoral  de  la 
France,"  pubhshed  in  1832. 

They  divide  the  area  included  between  high- 
water-mark  and  lowwater-mark  of  spring  tides 
(which  is  very  extensive,  on  account  of  the  great 
rise  and  fall  of  the  tide  on  the  Normandy  coast 
about  St,  Malo,  where  their  observations  were 
made)  into  four  zones,  each  characterized  by  its 
peculiar  invertebrate  inhabitants.  Beyond  the 
fourth  region  they  distinguish  a  fifth,  which  is 
never  uncovered,  and  is  inhabited  by  oysters, 
scallops,  and  large  starfishes  and  other  animals. 
Beyond  this  they  seem  to  think  that  animal  life 
is  absent.^ 

Audouin  and  Milne  Edwards  were  the  first  to 
see  the  importance  of  the  bearing  of  a  knowledge 
of  the  manner  in  which  marine  animals  are 
distributed  in  depth,  on  geology.  They  suggest 
that,  by  this  means,  it  will  be  possible  to  judge 
whether  a  fossiliferous  stratum  was  formed  upon 
the  shore  of  an  ancient  sea,  and  even  to  determine 
whether  it  was  deposited  in  shallower  or  deeper 
water  on  that  shore ;  the  association  of  shells  of 
animals  which  live  in  different  zones  of  depth  will 

^  ".  Enfin  plus  bas  encore,  c'est-k-dire  alors  loin  des  cotes,  le 
fond  des  eaux  ne  paraii  plus  etre  habite,  du  moins  dans  nos 
mers,  par  aucun  de  ces  animaux"  (1.  c.  torn.  i.  p.  237).  The 
*'ces  animaux  "  leaves  the  meaning  of  the  authors  doubtluL 


II      THE  PROBLEMS  OF  THE  DEEP  SEA     49 

prove  that  the  shells  have  been  transported  into 
the  position  in  which  they  are  found ;  while,  on 
the  other  hand,  the  absence  of  shells  in  a  deposit 
will  not  justify  the  conclusion  that  the  waters  in 
which  it  was  formed  were  devoid  of  animal  in- 
habitants, inasmuch  as  they  might  have  been  only 
too  deep  for  habitation. 

The  new  line  of  investigation  thus  opened  by 
the  French  naturalists  was  followed  up  by  the 
Norwegian,  Sars,  in  1835,  by  Edward  Forbes,  in 
our  own  country,  in  1840,^  and  by  (Ersted,  in 
Denmark,  a  few  years  later.  The  genius  of 
Forbes,  combined  wdth  his  extensive  knowledge  of 
botany,  invertebrate  zoology,  and  geology,  enabled 
him  to  do  more  than  any  of  his  compeers,  in 
bringing  the  importance  of  distribution  in  depth 
into  notice ;  and  his  researches  in  the  iEgean  Sea, 

^  In  the  paper  in  the  Memoirs  of  the  Survey  cited  further  on, 
Forbes  writes  : — 

"In  an  essay  'On  the  Association  of  Mollusca  on  the 
British  Coasts,  considered  with  reference  to  Pleistocene 
Geology,'  printed  in  [the Edinhurcfh  Academic  Anvuciliox]  1840, 
I  described  the  mollusca,  as  distributed  on  our  shores  and  seas, 
in  four  great  zones  or  regions,  usually  denominated  '  The  Lit- 
toral Zone,'  'The  region  of  Laminarine,'  ' The  region  of  Coral- 
lines,' and  'The  region  of  Corals.'  An  extensive  series  of 
re  earches,  chiefly  conducted  by  the  members  of  the  committee 
appointed  by  the  British  Association  to  investigate  the  nsarine 
geology  of  Britain  by  means  of  the  dredge,  have  not  invalidati-d 
this  classification,  and  the  researches  of  Professor  Loven,  in  the 
Norwegian  and  Lapland  seas,  have  borne  out  their  correctness. 
The  first  two  of  the  regions  above  mentioned  had  been  previ- 
ously noticed  by  Lamouroux,  in  his  account  of  the  distribution 
(vertically)  of  sea-weeds,  by  Audouin  and  Milne  Edwards  in  • 
their  ObiiervcUions  on  the  Natural  History  of  the  coast  of  France^ 
ami  by  Sai's  in  the  preface  to  his  Bcskriielssr  og  Jagttajelser.'* 

190 


50  THE   PROBLEMS   OF   THE  DEEP   SEA  il 

and  still  more  his  remarkable  paper  "  On  the  Geo- 
logical Relations  of  the  existing  Fauna  and  Flora  of 
the  British  Isles,"  published  in  1846,  in  the  first 
volume  of  the  "  Memoirs  of  the  Geological  Survey 
of  Great  Britain,"  attracted  universal  attention. 

On  the  coasts  of  the  British  Islands,  Forbes 
distinguishes  four  zones  or  regions,  the  Littoral 
(between  tide  marks),  the  Laminarian  (between 
lowwater-mark  and  15  fathoms),  the  Coralline 
(from  15  to  50  fathoms),  and  the  Deep  sea 
or  Coral  region  (from  50  fathoms  to  beyond  100 
fathoms).  But,  in  the  deeper  waters  of  the  ^Egean 
Sea,  between  the  shore  and  a  depth  of  300 
fathoms,  Forbes  was  able  to  make  out  no  fewer 
than  eight  zones  of  life,  in  the  course  of  which  the 
number  and  variety  of  forms  gi^adually  diminished ; 
until,  beyond  300  ikthoms,  life  disappeared  alto- 
gether. Hence  it  appeared  as  if  descent  in  the 
sea  had  much  the  same  effect  on  life,  as  ascent 
on  land.  Recent  investigations  appear  to  show 
that  Forbes  was  right  enough  in  his  classification 
of  the  facts  of  distribution  in  depth  as  they  are  to 
be  observed  in  the  iEgean ;  and  though,  at  the 
time  he  wrote,  one  or  two  observations  were 
extant  which  might  have  warned  him  not  to 
generalize  too  extensively  from  his  ^gean  ex- 
perience, his  own  dredging  work  was  so  much 
more  extensive  and  systematic  than  that  of  any 
other  naturalist,  that  it  is  not  wonderful  he  should 
have  felt  justified  in  building  upon  it.     Never* 


n      THE  PROBLEMS  OF  THE  DEEP  SEA     51 

theless,  so  far  as  the  limit  of  the  range  of  life  in 
depth  goes,  Forbes'  conclusion  has  been  completely- 
negatived,  and  the  greatest  depths  yet  attained 
show  not  even  an  approach  to  a  "  zero  of  life  "  : — ■ 

"  During  the  several  cruises  of  H.  M.  ships  Lightning  and 
Porcwpine  in  the  years  1868,  1869,  and  1870,"  says  Dr.  Wyville 
Thomson,  "fifty-seven  hauls  of  the  dredge  were  taken  in  the 
Atlantic  at  depths  beyond  500  fathoms,  and  sixteen  at  depths 
beyond  1,000  fathoms,  and,  in  all  cases,  life  was  abundant.  In 
1869,  we  took  two  casts  in  depths  greater  than  2,000  fathoms. 
In  both  of  these  life  was  abundant  ;  and  with  the  deepest  cast, 
2,435  fathoms,  off  the  mouth  of  the  Bay  of  Biscay,  we  took 
living,  well-marked  and  characteristic  examples  of  all  the  five 
invertebrate  sub  kingdoms.  And  thus  the  question  of  the 
existence  of  abundant  animal  life  at  the  bottom  of  the  sea  has 
been  finally  settled  and  for  all  depths,  for  there  is  no  reason 
to  suppose  that  the  depth  anywhere  exceeds  bettveen  three  and 
four  thousand  fathoms  ;  and  if  there  be  nothing  in  the  condi- 
tions of  a  depth  of  2,500  fathoms  to  prevent  the  full  develop- 
ment of  a  varied  Fauna,  it  is  impossible  to  suppose  that  even  an 
additional  thousand  fathoms  would  make  any  gi'eat  difference,"^ 

As  Dr.  Wyville  Thomson's  recent  letter,  cited 
above,  shows,  the  use  of  the  trawl,  at  great  depths, 
has  brought  to  light  a  still  greater  diversity  of  life. 
Fishes  came  up  from  a  depth  of  600  to  more  than 

1  The  Depths  of  the  Sea,  p.  30.  Results  of  a  similar  kind, 
obtained  by  previous  observers,  are  stated  at  length  in  the  sixth 
chapter,  pp.  267-280.  The  dredgings  carried  out  by  Count 
Pourtales,  under  the  authority  of  Professor  Peirce,  the  Super- 
intendent of  the  United  States  Coast  Survey,  in  the  years 
1867,  1868,  and  1869,  are  particularly  noteworthy,  and  it  is 
probably  not  too  much  to  say,  in  the  words  of  Professor 
Agassiz,  "that  we  owe  to  the  coast  survey  the  first  broad  and 
comprehensive  basis  for  an  exploration  of  the  sea  bottom  on  a 
large  scale,  opening  a  new  era  in  zoolodcal  and  geological 
research." 


52     THE  PROBLEMS  OF  THE  DEEP  SEA     ii 

1,000  fathoms,  all  "in  a  peculiar  condition  from 
the  expansion  of  the  air  contained  in  their  bodies. 
On  their  relief  from  the  extreme  pressure,  their 
eyes,  especially,  had  a  singular  appearance,  pro- 
truding like  great  globes  from  their  heads." 
Bivalve  and  univalve  mollusca  seem  to  be  rare  at 
the  greatest  depths;  but  starfishes,  sea  urchins, 
and  other  echinoderms,  zoophytes,  sponges,  and 
protozoa  abound. 

It  is  obvious  that  the  Challenger  has  the 
privilege  of  opening  a  new  chapter  in  the  history 
of  the  living  world.  She  cannot  send  down  her 
dredges  and  her  trawls  into  these  virgin  depths  of 
the  great  ocean  without  bringing  up  a  discovery. 
Even  though  the  thing  itself  may  be  neither 
"  rich  nor  rare,"  the  fact  that  it  came  from  that 
depth,  in  that  particular  latitude  and  longitude, 
will  be  a  new  fact  in  distribution,  and,  as  such, 
have  a  certain  importance. 

But  it  may  be  confidently  assumed  that  the 
things  brought  up  will  very  frequently  be  zoo- 
logical novelties;  or,  better  still,  zoological 
antiquities,  which,  in  the  tranquil  and  little- 
changed  depths  of  the  ocean,  have  escaped  the 
causes  of  destruction  at  Avork  in  the  shallows,  and 
represent  the  predominant  population  of  a  past 
age. 

It  has  been  seen  that  Audouin  and  Milne 
Edwards  foresaw  the  general  influence  of  the 
Btudy  of  distribution  in  depth  upon  the  interpreta- 


n  THE   PROBLEMS   OF   THE   DEEP   SEA  53 

tion  of  geological  phenomena.  Forbes  connected 
the  two  orders  of  inquiry  still  more  closely ;  and 
in  the  thoughtful  essay  "  On  the  connection  be- 
tween the  distribution  of  the  existing  Fauna  and 
Flora  of  the  British  Isles,  and  the  geological 
changes  which  have  affected  their  area,  especially 
during  the  epoch  of  the  Northern  drift,"  to  which 
reference  has  already  been  made,  he  put  forth  a 
most  pregnant  suggestion. 

In  certain  parts  of  the  sea  bottom  in  the  imme- 
diate vicinity  of  the  British  Islands,  as  in  the 
Clyde  district,  among  the  Hebrides,  in  the  Moray 
Firth,  and  in  the  German  Ocean,  there  are  de- 
pressed areae,  forming  a  kind  of  submarine  valleys, 
the  centres  of  which  are  from  80  to  100  fathoms, 
or  more,  deep.  These  depressions  are  inhabited 
by  assemblages  of  marine  animals,  which  differ 
from  those  found  over  the  adjacent  and  shallower 
region,  and  resemble  those  which  are  met  with 
much  farther  north,  on  the  Norwegian  coast. 
Forbes  called  these  Scandinavian  detachments 
"  Northern  outliers." 

How  did  these  isolated  patches  of  a  northern 
population  get  into  these  deep  places?  To 
explain  the  mystery,  Forbes  called  to  mind  the 
fact  that,  in  the  epoch  which  immediately  pre- 
ceded the  present,  the  climate  was  much  colder 
(whence  the  name  of  "  glacial  epoch  "  applied  to 
it) ;  and  that  the  shells  which  are  found  fossil,  or 
sub-fossil,  in  deposits  of  that  age  are  precisely  such 


54  THE   PROBLEMS   OF   THE   DEEP  SEA  ii 

as  are  now  to  be  met  with  only  in  the  Scandinavian, 
or  still  more  Arctic,  regions.  Undoubtedly,  during 
the  glacial  epoch,  the  general  population  of  our 
seas  had,  universally,  the  northern  aspect  which 
is  now  presented  only  by  the  "  northern  outliers  "; 
just  as  the  vegetation  of  the  land,  do^vn  to  the 
sea-level,  had  the  northern  character  which  is,  at 
present,  exhibited  only  by  the  plants  which  live 
on  the  tops  of  our  mountains.  But,  as  the  glacial 
epoch  passed  away,  and  the  present  climatal  con- 
ditions were  developed,  the  northern  plants  were 
able  to  maintain  themselves  only  on  the  bleak 
heio-hts,  on  which  southern  forms  could  not  com- 
pete  with  them.  And,  in  like  manner,  Forbes  sug- 
gested that,  after  the  glacial  epoch,  the  northern 
animals  then  inhabiting  the  sea  became  restricted 
to  the  deeps  in  which  they  could  hold  their 
own  against  invaders  from  the  south,  better  fitted 
than  they  to  flourish  in  the  warmer  waters  of  the 
shallows.  Thus  depth  in  the  sea  corresponded  in 
its  effect  upon  distribution  to  height  on  the 
land. 

The  same  idea  is  applied  to  the  explanation  of 
a  similar  anomaly  in  the  Fauna  of  the  ^gean  : — 

"  In  the  deepest  of  the  regions  of  depth  of  the  MgesLU,  the 
representation  of  a  Northern  Fauna  is  maintained,  partly  by 
iilentical  and  partly  by  representative  forms.  .  .  .  The  presence 
of  the  latter  is  essentially  due  to  the  law  (of  representation  of 
parallels  of  latitude  by  zones  of  depth),  whilst  that  of  the 
former  species  depended  on  their  transmission  from  their  parent 
seas  during  a  former  epoch,  and  subsequent  isolation.     That 


ir      THE  PROBLEMS  OF  THE  DEEP  SEA     55 

epoch  was  doubtless  the  newer  Pliocene  or  Glacial  Era.,  when  the 
Mya  tricnc  da  and  other  northern  forms  now  extinct  in  the 
Mediterranean,  and  found  fossil  in  the  Sicilian  tertiaries, 
ranged  into  tliat  sea.  The  changes  which  there  destroyed  the 
shallow  water  glacial  forms,  did  not  affect  those  living  in  the 
depths,  and  which  still  survive."  ^ 

The  conception  that  the  inhabitants  of  local 
depressions  of  the  sea  bottom  might  be  a  remnant 
of  the  ancient  population  of  the  area,  which  had 
held  their  own  in  these  deep  fastnesses  against  an 
invading  Fauna,  as  Britons  and  Gaels  have  held 
out  in  Wales  and  in  Scotland  against  encroaching 
Teutons,  thus  broached  by  Forbes,  received  a 
wider  application  than  Forbes  had  dreamed  of 
when  the  sounding  machine  first  brought  up 
specimens  of  the  mud  of  the  deep  sea.  As  I  have 
pointed  out  elsewhere,^  it  at  once  became  obvious 
that  the  calcareous  sticky  mud  of  the  Atlantic 
was  made  up,  in  the  main,  of  shells  of  Glohigerina 
and  other  Foraminifera,  identical  with  those  of 
which  the  true  chalk  is  composed,  and  the  identity 
extended  even  to  the  presence  of  those  singailar 
bodies,  the  Coccoliths  and  Coccospheres,  the  true 
nature  of  which  is  not  yet  made  out.  Here  then 
were  organisms,  as  old  as  the  cretaceous  epoch, 
still  alive,  and  doing  their  work  of  rock-making  at 
the  bottom  of  existing  seas.     What  if  GloUgerina 

^  Memoirs  of  the  Geological  Survey  of  Great  Britain,  Yol  i 
p.  390. 
^  See  above,  "On  a  Piece  of  Chalk,"  p.  13. 


56     THE  PROBLEMS  OF  THE  DEEP  SEA      ii 

and  the  Coccoliths  should  not  be  the  only  sur- 
vivors of  a  world  passed  away,  Avhich  are  hidden 
beneath  three  miles  of  salt  water?  The  letter 
which  Dr.  Wyville  Thomson  wrote  to  Dr.  Car- 
penter in  May,  1868,  out  of  which  all  these  expe- 
ditions have  grown,  shows  that  this  query  had 
become  a  practical  problem  in  Dr.  Thomson's 
mind  at  that  time ;  and  the  desirableness  of 
solving  the  problem  is  put  in  the  foregTound  of 
his  reasons  for  urging  the  Government  to  under- 
take the  work  of  exploration : — 

**  Two  years  ago,  M.  Sars,  Swedish  Government  Inspector  of 
Fisheries,  had  an  opportunity,  in  his  official  capacity,  of  dredg- 
ing off  the  Loffoten  Islands  at  a  depth  of  300  fathoms.  I 
visited  Norway  shortly  after  his  return,  and  had  an  opportunity 
of  studying  with  his  father,  Professor  Sars,  some  of  his  results. 
Animal  forms  were  abundant;  many  of  them  were  new  to 
science  ;  and  among  them  was  one  of  surpassing  interest,  the 
small  crinoid,  of  which  you  have  a  specimen,  and  which  we  at 
once  recognised  as  a  degraded  type  of  the  Apiocrinidoi,  an  order 
hitherto  regarded  as  extinct,  which  attained  its  maximum  in 
the  Pear  Encrinites  of  the  Jurassic  period,  and  whose  latest 
representative  hitherto  known  was  the  Bourgurftocrinus  of  the 
chalk.  Some  years  previously,  Mr.  Absjornsen,  dredging  in  200 
fathoms  in  the  Hardangerfjord,  procured  several  examples  of  a 
Starfish  {Brisinga),  which  seems  to  find  its  nearest  ally  in  the 
fossil  genus  Protaster.  These  observations  place  it  beyond  a 
doubt  that  animal  life  is  abundant  in  the  ocem  at  depths 
varying  from  200  to  300  fathoms,  that  the  forms  at  these  great 
depths  differ  greatly  from  those  met  within  ordinary  dredgings, 
and  that,  at  all  events  in  some  cases,  these  animals  are  closely 
allied  to,  and  would  seem  to  be  directly  descended  from,  the 
Fauna  of  the  early  tertiaries. 

"I  think  the  latter  result  might  almost  have  been  antici- 


ri      THE  PROBLEMS  OF  THE  DEEP  SEA     57 

pated  ;  and,  probably,  further  investigation  will  largely  add  to 
this  class  of  data,  and  will  give  us  an  opportunity  of  testing 
our  determinations  of  the  zoological  position  of  some  fossil 
types  by  an  examination  of  the  soft  parts  of  their  recent 
representatives.  The  main  cause  of  the  destruction,  the  migra- 
tion, and  the  extreme  modification  of  animal  types,  appear  to 
be  change  of  climate,  chiefly  depending  upon  oscillations  of  the 
earth's  crust.  These  oscillations  do  not  appear  to  have  ranged, 
in  the  Northern  portion  of  the  Northern  Hemisphere,  much 
beyond  1,000  feet  since  the  commencement  of  the  Tertiary 
Epoch.  The  temperature  of  deep  waters  seems  to  be  constant 
for  all  latitudes  at  39" ;  so  that  an  immense  area  of  the  North 
Atlantic  must  have  had  its  conditions  unaffected  by  tertiary  or 
post- tertiary  oscillations."  ^ 

As  we  shall  see,  the  assumption  that  the  tem- 
perature of  the  deep  sea  is  everywhere  39°  F.  (4° 
Cent.)  is  an  error,  which  Dr.  Wyville  Thomson 
adopted  from  eminent  physical  writers ;  but  the 
general  justice  of  the  reasoning  is  not  affected  by 
this  circumstance,  and  Dr.  Thomson's  expectation 
has  been,  to  some  extent,  already  verified. 

Thus  besides  Glohigerina,  there  are  eighteen 
species  of  deep-sea  Foraminifera  identical  with 
species  found  in  the  chalk.  Imbedded  in  the 
chalky  mud  of  the  deep  sea,  in  many  locali- 
ties, are  innumerable  cup-shaped  sponges,  pro- 
vided with  six-rayed  silicious  spicula,  so  disposed 
that  the  wall  of  the  cup  is  formed  of  a 
lace  work  of  flinty  thread.  Not  less  abundant, 
in  some  parts  of  the  chalk  formation,  are  the 
fossils  known  as    Ventriculites,  well  described  by 

1  The  Depths  of  the  Sea,  pp.  51-52, 


58     THE  PROBLEMS  OF  THE  DEEP  SEA      n 

Dr.  Thomson  as  "  elegant  vases  or  cups,  with 
branching  root-hke  bases,  or  groups  of  regularly 
or  irregularly  spreading  tubes  delicately  fretted 
on  the  surface  with  an  impressed  network  like 
the  finest  lace " ;  and  he  adds,  "  When  we  com- 
pare such  recent  forms  as  Aphrocallistes,  IpMtcon, 
Holtmia,  and  Askonema,  with  certain  series  of  the 
chalk  Ventriculites,  there  cannot  be  the  slightest 
doubt  that  they  belong  to  the  same  family — in 
some  cases  to  very  nearly  allied  genera."  ^ 

Professor  Duncan  finds  "  several  corals  from  the 
coast  of  Portugal  more  nearly  allied  to  chalk  forms 
than  to  any  others." 

The  Stalked  Crinoids  or  Feather  Stars,  so 
abundant  in  ancient  times,  are  now  exclusively 
confined  to  the  deep  sea,  and  the  late  explorations 
have  yielded  forms  of  old  afiinity,  the  existence 
of  which  has  hitherto  been  unsuspected.  The 
general  character  of  the  group  of  star  fishes 
imbedded  in  the  white  chalk  is  almost  the  same 
as  in  the  modern  Fauna  of  the  deep  Atlantic. 
The  sea  urchins  of  the  deep  sea,  while  none  of 
them  are  specifically  identical  with  any  chalk 
form,  belong  to  the  same  general  groups,  and 
some  closely  approach  extinct  cretaceous  genera. 

Taking  these  facts  in    conjunction    with    the 

positive  evidence    of   the    existence,  during  the 

Cretaceous  epoch,  of  a  deep  ocean  where  now  lies 

the  dry  land  of   central  and   southern    Europe, 

1  The  Depths  of  the  Sea,  p.  484. 


II      THE  PROBLEMS  OF  THE  DEEP  SEA     59 

northern  Africa,  and  western  and  southern  Asia ; 
and  of  the  gradual  diminution  of  this  ocean 
during  the  older  tertiary  epoch,  until  it  is 
represented  at  the  present  day  by  such  teacup- 
fuls  as  the  CasjDian,  the  Black  Sea,  and  the 
Mediterranean;  the  supposition  of  Dr.  Thomson 
and  Dr.  Carpenter  that  what  is  now  the  deep 
Atlantic,  was  the  deep  Atlantic  (though  merged 
in  a  vast  easterly  extension)  in  the  Cretaceous 
epoch,  and  that  the  Glohigerina  mud  has  been 
accumulating  there  from  that  time  to  this,  seems 
to  me  to  have  a  great  degree  of  probability.  And 
I  agree  with  Dr.  Wyville  Thomson  against  Sir 
Charles  Lyell  (it  takes  two  of  us  to  have  any 
chance  against  his  authority)  in  demurring  to  the 
assertion  that  "  to  talk  of  chalk  having  been 
uninterruptedly  formed  in  the  Atlantic  is  as 
inadmissible  in  a  geographical  as  in  a  geological 
sense." 

If  the  word  "  chalk "  is  to  be  used  as  a 
stratigraphical  term  and  restricted  to  Glohigerina 
mud  deposited  during  the  Cretaceous  epoch,  of 
course  it  is  improper  to  call  the  precisely  similar 
mud  of  more  recent  date,  chalk.  If,  on  the  other 
hand,  it  is  to  be  used  as  a  mineralogical  term,  I 
do  not  see  how  the  modem  and  the  ancient 
chalks  are  to  be  separated — and,  looking  at  the 
matter  geographically,  I  see  no  reason  to  doubt 
that  a  boring  rod  driven  from  the  surface  of  the 
mud  which  forms  the  floor  of  the  mid-Atlantic 


60  THE   PROBLEMS    OF   THE   DEEP   SEA  II 

would  pass  through  one  continuous  mass  of 
GloUgerina  mud,  first  of  modern,  then  of  tertiary, 
and  then  of  mesozoic  date ;  the  "  chalks "  of 
different  depths  and  ages  being  distinguished 
merely  by  the  different  forms  of  other  organisms 
associated  with  the  Glohigerince. 

On  the  other  hand,  I  think  it  must  be  admitted 
that  a  belief  in  the  continuity  of  the  modern  with 
the  ancient  chalk  has  nothing  to  do  with  the 
proposition  that  we  can,  in  any  sense  whatever, 
be  said  to  be  still  living  in  the  Cretaceous  epoch. 
When  the  Challengers  trawl  brings  up  an  Ich- 
thyosaurtcs,  along  with  a  few  Hving  specimens 
of  Belemnites  and  Tumlites,  it  may  be  admitted 
that  she  has  come  upon  a  cretaceous  "  outlier." 
A  geological  period  is  characterized  not  only 
by  the  presence  of  those  creatures  which  lived 
in  it,  but  by  the  absence  of  those  which  have 
only  come  into  existence  later;  and,  however 
large  a  proportion  of  true  cretaceous  fonns  may 
be  discovered  in  the  deep  sea,  the  modem  types 
associated  with  them  must  be  abolished  before 
the  Fauna,  as  a  whole,  could,  with  any  propriety, 
be  termed  Cretaceous. 

I  have  now  indicated  some  of  the  chief  lines  of 
Biological  inquiry,  in  which  the  Challenger  has 
special  opportunities  for  doing  good  service,  and 
in  following  which  she  will  be  carrying  out  the 
work  already  commenced  by  the  Lightning  and 


n      THE  PROBLEMS  OF  THE  DEEP  SEA     61 

Porcu]pine  in  their  cruises  of  1868  and  subsequent 
years. 

But  biology,  in  the  long  run,  rests  upon  physics, 
and  the  first  condition  for  arriving  at  a  sound 
theory  of  distribution  in  the  deep  sea,  is  the 
precise  ascertainment  of  the  conditions  of  life; 
or,  in  other  words,  a  full  knowledge  of  all  those 
phenomena  which  are  embraced  under  the  head 
of  the  Physical  Geogi^aphy  of  the  Ocean. 

Excellent  work  has  already  been  done  in  this 
direction,  chiefly  under  the  superintendence  of  Dr. 
Carpenter,  by  the  Lightning  and  the  Porcupine} 
and  some  data  of  fundamental  importance  to  the 
physical  geography  of  the  sea  have  been  fixed 
beyond  a  doubt. 

Thus,  though  it  is  true  that  sea-water  steadily 
contracts  as  it  cools  doA\Ti  to  its  freezing  point, 
instead  of  expanding  before  it  reaches  its  freezing 
point  as  fresh  water  does,  the  truth  has  been 
steadily  ignored  by  even  the  highest  authorities 
in  physical  geography,  and  the  erroneous  con- 
clusions deduced  from  their  erroneous  premises 
have  been  widely  accepted  as  if  they  were 
ascertained  facts.  Of  course,  if  sea-water,  like 
fresh  water,  were  heaviest  at  a  temperature  of 
39°  F.  and  got  lighter  as  it  approached  32°  R, 
the  water  of  the  bottom  of  the  deep  sea  could  not 
be  colder  than  39°.  But  one  of  the  first  results 
s>f  the  careful  ascertainment  of  the  temperature 
*  FroGcedings  of  the  Royal  Society,  1870  and  1872. 


62     THE  PROBLEMS  OF  THE  DEEP  SEA      n 

at  different  depths,  by  means  of  thermometers 
specially  contrived  for  the  avoidance  of  the  errors 
produced  by  pressure,  was  the  proof  that,  below 
1000  fathoms  in  the  Atlantic,  down  to  the  greatest 
depths  yet  sounded,  the  water  has  a  temperature 
always  lower  than  38°  Fahr.,  whatever  be  the 
temperature  of  the  water  at  the  surface.  And 
that  this  low  temperature  of  the  deepest  water 
is  probably  the  universal  rule  for  the  depths  of 
the  open  ocean  is  sho^vn,  among  others,  by  Captain 
Chimmo's  recent  observations  in  the  Indian  ocean, 
between  Ceylon  and  Sumatra,  where,  the  surface 
water  ranging  from  85° — 81°  Fahr.,  the  tempera- 
ture at  the  bottom,  at  a  depth  of  2270  to  2656 
fathoms,  was  only  from  34°  to  32°  Fahr. 

As  the  mean  temjDerature  of  the  superficial 
layer  of  the  crust  of  the  earth  may  be  taken  at 
about  50°  Fahr.,  it  follows  that  the  bottom  layer 
of  the  deep  sea  in  temperate  and  hot  latitudes, 
is,  on  the  average,  much  colder  than  either  of  the 
bodies  with  which  it  is  in  contact ;  for  the  tem- 
perature of  the  earth  is  constant,  while  that  of 
the  air  rarely  falls  so  low  as  that  of  the  bottom 
water  in  the  latitudes  in  question ;  and  even  when 
it  does,  has  time  to  affect  only  a  comparatively 
thin  stratum  of  the  surface  water  before  the 
return  of  warm  weather. 

How  does  this  apparently  anomalous  state  of 
things  come  about  ?  If  we  suppose  the  globe  to 
be  covered  with  a  universal  ocean,  it  can  hardly 


II      THE  PROBLEMS  OF  THE  DEEP  SEA     63 

be  doubted  that  the  cold  of  the  regions  towards 
the  poles  must  tend  to  cause  the  suj)erficial  water 
of  those  regions  to  contract  and  become  specifically 
heavier.  Under  these  circumstances,  it  would 
have  no  alternative  but  to  descend  and  spread 
over  the  sea  bottom,  while  its  place  would  be 
taken  by  warmer  water  drawn  from  the  adjacent 
regions.  Thus,  deep,  cold,  polar-equatorial  currents, 
and  superficial,  warmer,  equatorial-polar  currents, 
would  be  set  up ;  and  as  the  former  would  have 
a  less  velocity  of  rotation  from  west  to  east  than 
the  regions  towards  which  they  travel,  they  would 
not  be  due  southerly  or  northerly  currents,  but 
south-westerly  in  the  northern  hemisphere,  and 
north-westerly  in  the  southern ;  while,  by  a  parity 
of  reasoning,  the  equatorial-polar  warm  currents 
would  be  north-easterly  in  the  northern  hemi- 
sphere, and  south-easterly  in  the  southern.  Hence, 
as  a  north-easterly  cuiTent  has  the  same  direction 
as  a  south-westerly  wind,  the  direction  of  the 
northern  equatorial-polar  current  in  the  extra- 
tropical  part  of  its  course  would  pretty  nearly 
coincide  with  that  of  the  anti-trade  winds.  The 
freezing  of  the  surface  of  the  polar  sea  would  not 
interfere  with  the  movement  thus  set  up.  For, 
however  bad  a  conductor  of  heat  ice  may  be,  the 
unfrozen  sea-water  immediately  in  contact  with 
the  undersurface  of  the  ice  must  needs  be  colder 
than  that  further  off ;  and  hence  will  constantly  tend 
to  descend  through  the  subjacent  warmer  water. 


64  THE   PROBLEMS   OF   THE   DEEP   SEA  ii 

111  this  way,  it  would  seem  inevitable  that  the 
surface  waters  of  the  northern  and  southern  frigid 
zones  must,  sooner  or  later,  find  their  way  to  the 
bottom  of  the  rest  of  the  ocean;  and  there  ac- 
cumulate to  a  thickness  dependent  on  the  rate  at 
which  they  absorb  heat  from  the  crust  of  the  earth 
below,  and  from  the  surface  water  above. 

If  this  hypothesis  be  correct,  it  follows  that,  if 
any  part  of  the  ocean  in  warm  latitudes  is  shut 
off  from  the  influence  of  the  cold  polar  underflow, 
the  temperature  of  its  deeps  should  be  less  cold 
than  the  temperature  of  corresponding  depths  in 
the  open  sea.  Now,  in  the  Mediterranean,  Nature 
ofters  a  remarkable  experimental  proof  of  just  the 
kind  needed.  It  is  a  landlocked  sea  which  runs 
nearly  east  and  west,  between  the  twenty-ninth 
and  forty-fifth  23arallels  of  north  latitude.  Roughly 
speaking,  the  average  temperature  of  the  air  over 
it  is  75°  Fahr.  in  July  and  48°  in  January. 

This  great  expanse  of  water  is  divided  by  the 
peninsula  of  Italy  (including  Sicily),  continuous 
with  which  is  a  submarine  elevation  carrying  less 
than  1,200  feet  of  water,  which  extends  from 
Sicily  to  Cape  Bon  in  Africa,  into  two  great  pools 
■ — an  eastern  and  a  western.  The  eastern  pool 
rapidly  deepens  to  more  than  12,000  feet,  and 
sends  off  to  the  north  its  comparatively  shallow 
branches,  the  Adriatic  and  the  ^gean  Seas.  The 
western  pool  is  less  deep,  though  it  reaches  some 
10,000  feet.     And,  just  as  the  western  end  of  the 


n      THE  PROBLEMS  OF  THE  DEEP  SEA     65 

eastern  pool  communicates  by  a  shallow  passage, 
not  a  sixth  of  its  greatest  depth,  with  the  western 
pool,  so  the  western  pool  is  separated  jfrom  the 
Atlantic  by  a  ridge  which  runs  between  Capes 
Trafalgar  and  Spartel,  on  which  there  is  hardly 
1,000  feet  of  water.  All  the  water  of  the  Mediter- 
ranean which  lies  deeper  than  about  150  fathoms, 
therefore,  is  shut  off  from  that  of  the  Atlantic, 
and  there  is  no  communication  between  the  cold 
layer  of  the  Atlantic  (below  1,000  fathoms)  and 
the  Mediterranean.  Under  these  circumstances, 
what  is  the  temperature  of  the  Mediterranean  ? 
Every^vhere  below  600  feet  it  is  about  55°  Fahr. ; 
and  consequently,  at  its  greatest  depths,  it  is  some 
20°  warmer  than  the  corresponding  depths  of  the 
Atlantic. 

It  seems  extremely  difficult  to  account  for  this 
difference  in  any  other  way,  than  by  adopting 
the  views  so  strongly  and  ably  advocated  by  Dr. 
Carpenter,  that,  in  the  existing  distribution  of 
land  and  water,  such  a  circulation  of  the  water  of 
the  ocean  does  actually  occur,  as  theoretically  must 
occur,  in  the  universal  ocean,  with  which  we 
started. 

It  is  quite  another  question,  however,  whether 
this  theoretic  circulation,  true  cause  as  it  may  be, 
is  competent  to  give  rise  to  such  movements  of 
sea-water,  in  mass,  as  those  currents,  which  have 
commonly  been  regarded  as  northern  extensions  of 
the  Gulf-stream.     I  shall  not  venture  to  touch 

191 


6Q  THE  PROBLEMS  OF  THE  DEEP  SEA      n 

upon  this  complicated  problem ;  but  I  may  take 
occasion  to  remark  that  tbe  cause  of  a  much 
simpler  phenomenon — the  stream  of  Atlantic 
water  which  sets  through  the  Straits  of  Gibraltar, 
eastward,  at  the  rate  of  two  or  three  miles  an  hour 
or  more,  does  not  seem  to  be  so  clearly  made  out 
as  is  desirable. 

The  facts  appear  to  be  that  the  water  of  the 
Mediterranean  is  very  slightly  denser  than  that  of 
the  Atlantic  (1-0278  to  1-0265),  and  that  the  deep 
water  of  the  Mediterranean  is  slightly  denser  than 
that  of  the  surface ;  while  the  deep  water  of  the 
Atlantic  is,  if  anything,  Hghter  than  that  of  the 
surface.  Moreover,  while  a  rapid  superficial  cur- 
rent is  setting  in  (always,  save  in  exceptionally 
violent  easterly  winds)  through  the  Straits  of 
Gibraltar,  from  the  Atlantic  to  the  Mediterranean, 
a  deep  undercurrent  (together  with  variable  side 
currents)  is  setting  out  through  the  Straits,  from 
the  Mediterranean  to  the  Atlantic. 

Dr.  Carpenter  adopts,  without  hesitation,  the 
view  that  the  cause  of  this  indraught  of  Atlantic 
water  is  to  be  sought  in  the  much  more  rapid 
evaporation  which  takes  place  from  the  surface  of 
the  Mediterranean  than  from  that  of  the  Atlantic  ; 
and  thus,  by  lowering  the  level  of  the  former,  gives 
rise  to  an  indraught  from  the  latter. 

But  is  there  any  sound  foundation  for  the  three 
assumptions  involved  here?  Firstly,  that  the 
evaporation  from  the  Mediterranean,  as  a  whole, 


n      THE  PROBLEMS  OF  THE  DEEP  SEA     67 

is  mucli  greater  tlian  that  from  the  Atlantic  under 
corresponding  parallels ;  secondly,  that  the  rainfall 
over  the  Mediterranean  makes  up  for  evaporation 
less  than  it  does  over  the  Atlantic ;  and  thirdly, 
supposing  these  two  questions  answered  affirm- 
atively; Are  not  these  sources  of  loss  in  the 
Mediterranean  fully  covered  by  the  prodigious 
quantity  of  fresh  water  which  is  poured  into  it  by 
great  rivers  and  submarine  springs  ?  Consider 
that  the  water  of  the  Ebro,  the  Rhine,  the  Po,  the 
Danube,  the  Don,  the  Dnieper,  and  the  Nile,  all 
flow  directly  or  indirectly  into  the  Mediterranean ; 
that  the  volume  of  fresh  water  which  they  pour 
into  it  is  so  enormous  that  fresh  water  may  some- 
times be  baled  up  from  the  surface  of  the  sea  off 
the  Delta  of  the  Nile,  while  the  land  is  not  yet  in 
sight ;  that  the  water  of  the  Black  Sea  is  half  fresh, 
and  that  a  current  of  three  or  four  miles  an  hour 
constantly  streams  from  it  Mediterraneanwards 
through  the  Bosphorus; — consider,  in  addition, 
that  no  fewer  than  ten  submarine  springs  of  fresh 
water  are  known  to  burst  up  in  the  Mediterranean, 
some  of  them  so  large  that  Admiral  Smyth  calls 
them  "  subterranean  rivers  of  amazing  volume  and 
force " ;  and  it  would  seem,  on  the  face  of  the 
matter,  that  the  sun  must  have  enough  to  do  to 
keep  the  level  of  the  Mediterranean  down ;  and 
that,  possibly,  we  may  have  to  seek  for  the  cause 
of  the  small  superiority  in  saline  contents  of  the 
Mediterranean  water  in  some  condition  other  than 
solar  evaporation. 


68     THE  PROBLEMS  OF  THE  DEEP  SEA      n 

Again,  if  tlie  Gibraltar  indraught  is  the  effect  of 
evaporation,  why  does  it  go  on  in  Avinter  as  well 
as  in  summer  ? 

All  these  are  questions  more  easily  asked  than 
answered ;  but  they  must  be  answered  before  we 
can  accept  the  Gibraltar  stream  as  an  example 
of  a  current  produced  by  indraught  with  any 
comfort. 

The  Mediterranean  is  not  included  in  the 
Challengers  route,  but  she  will  visit  one  of  the 
most  promising  and  little  explored  of  hydro- 
graphical  regions — the  North  Pacific,  between 
Pol3rQesia  and  the  Asiatic  and  American  shores ; 
and  doubtless  the  store  of  observations  upon  the 
currents  of  this  region,  which  she  will  accumulate, 
when  compared  with  what  we  know  of  the  North 
Atlantic,  will  throw  a  powerful  light  upon  the 
present  obscurity  of  the  Gulf-stream  problera. 


Ill 


ON    SOME    OF    THE    RESULTS    OF    THE 
EXPEDITION  OF  H.M.S.  CHALLENGER 

[1875] 

In  May,  1873,  I  drew  attention^  to  the  im- 
portant problems  connected  with  the  physics 
and  natural  history  of  the  sea,  to  the  solu- 
tion of  which  there  was  every  reason  to  hope 
the  cruise  of  H.M.S.  Challenger  would  furnish 
important  contributions.  The  expectation  then 
expressed  has  not  been  disappointed.  Reports  to 
the  Admiralty,  papers  communicated  to  the  Royal 
Society,  and  large  collections  which  have  already 
been  sent  home,  have  shown  that  the  Challengers 
staff  have  made  admirable  use  of  their  gxeat 
opportunities;  and  that,  on  the  return  of  the 
expedition  in  1874,  their  performance  will  be  fully 
up  to  the  level  of  their  promise.  Indeed,  I  am 
disposed  to  go  so  far  as  to  say,  that  if  nothing 
more  came  of  the  Challengers  expedition  than 
^  See  the  preceding  Essay. 


70         EXPEDITION   OF  THE   "CHALLENGER"         m 

has  hitherto  been  yielded  by  her  exploration  of 
the  nature  of  the  sea  bottom  at  great  depths,  a 
fall  scientific  equivalent  of  the  trouble  and  ex- 
pense of  her  equipment  would  have  been  obtained. 
In  order  to  justify  this  assertion,  and  yet,  at  the 
same  time,  not  to  claim  more  for  Professor  Wyville 
Thomson  and  his  colleagues  than  is  their  due,  I 
must  give  a  brief  history  of  the  observations  which 
have  preceded  their  exploration  of  this  recondite 
field  of  research,  and  endeavour  to  make  clear 
what  was  the  state  of  knowledge  in  December, 
1872,  and  what  new  facts  have  been  added  by  the 
scientific  staff  of  the  Challenger.  So  far  as  I  have 
been  able  to  discover,  the  first  successful  attempt 
to  bring  up  from  great  depths  more  of  the  sea 
bottom  than  would  adhere  to  a  sounding-lead,  was 
made  by  Sir  John  Ross,  in  the  voyage  to  the 
Arctic  regions  which  he  undertook  in  1818.  In 
the  Appendix  to  the  narrative  of  that  voyage, 
there  will  be  found  an  account  of  a  very  ingenious 
apparatus  called  "  clams  " — a  sort  of  double  scoop 
— of  his  own  contrivance,  which  Sir  John  Eoss 
had  made  by  the  ship's  armourer ;  and  by  which, 
being  in  Baffin's  Bay,  in  72°  30'  N.  and  77°  15'  W., 
he  succeeded  in  bringing  up  from  1,050  fathoms 
(or  6,300  feet),  "  several  pounds  "  of  a  "  fine  green 
mud,"  which  formed  the  bottom  of  the  sea  in  this 
region.  Captain  (now  Sir  Edward)  Sabine,  who 
accompanied  Sir  John  Ross  on  this  cruise,  says  of 
this  mud  that  it  was  "  soft  and  greenish,  and  that 


in  EXPEDITION  OF   THE   "CHALLENGER"        71 

the  lead  sunk  several  feet  into  it."  A  similar 
"  fine  green  mud  "  was  found  to  compose  the  sea 
bottom  in  Davis  Straits  by  Goodsir  in  1845. 
Nothing  is  certainly  kno^vn  of  the  exact  nature  of 
the  mud  thus  obtained,  but  we  shall  see  that  the 
mud  of  the  bottom  of  the  Antarctic  seas  is  de- 
scribed in  curiously  similar  terms  by  Dr.  Hooker, 
and  there  is  no  doubt  as  to  the  compiDsition  of  this 
deposit. 

In  1850,  Captain  Penny  collected  in  Assistance 
Bay,  in  Kingston  Bay,  and  in  Melville  Bay, 
which  lie  between  73°  45'  and  74°  40'  N.,  speci- 
mens of  the  residuum  left  by  melted  surface  ice, 
and  of  the  sea  bottom  in  these  localities.  Dr. 
Dickie,  of  Aberdeen,  sent  these  materials  to 
Ehrenberg,  who  made  out  ^  that  the  residuum  of 
the  melted  ice  consisted  for  the  most  part  of  the 
silicious  cases  of  diatomaceous  plants,  and  of  the 
silicious  spicula  of  sponges ;  while,  mixed  with 
these,  were  a  certain  number  of  the  equally 
silicious  skeletons  of  those  low  animal  organisms, 
which  were  termed  Polycistinece  by  Ehrenberg,  but 
are  now  known  as  Radiolaria. 

In  1856,  a  very  remarkable  addition  to  our 
knowledo'e  of  the  nature  of  the  sea  bottom  in  high 
northern  latitudes  was  made  by  Professor  Bailey 
of  West  Point.  Lieutenant  Brooke,  of  the  United 
States  Navy,  who  was  employed  in  surveying  the 

^  Uebcr  ncue  AnscJiauungen  des  klcinsicn  vordlichen  Polar* 
lebens. — Monatsberichte  d.  K.  Akad.  Berlin,  1853. 


72         EXPEDITION   OF   THE   "CHALLENGER"         in 

Sea  of  Kamschatka,  had  succeeded  in  obtaining 
specimens  of  the  sea  bottom  from  gi'eater  depths 
than  any  hitherto  reached,  namely  from  2,700 
fathoms  (16,200  feet)  in  56°  46'  N.,  and  168°  18'  E. ; 
and  from  1,700  fathoms  (10,200  feet)  in  60°  15'  N- 
and  170°  53'  E.  On  examining  these  microscopically, 
Professor  Bailey  found,  as  Ehrenberg  had  done  in 
the  case  of  mud  obtained  on  the  opj^osite  side  of 
the  Arctic  region,  that  the  fine  mud  was  made  up 
of  shells  of  Biatcmacce,  of  spicula  of  sponges,  and 
of  Radiolaria,  with  a  small  admixture  of  mineral 
matters,  but  without  a  trace  of  any  calcareous 
organisms. 

Still  more  complete  information  has  been  ob- 
tained concerning  the  nature  of  the  sea  bottom 
in  the  cold  zone  aroimd  the  south  pole.  Between 
the  years  1839  and  1843,  Sir  James  Clark  Boss 
executed  his  famous  Antarctic  expedition,  in  the 
course  of  which  he  penetrated,  at  two  widely  dis- 
tant points  of  the  Antarctic  zone,  into  the  high 
latitudes  of  the  shores  of  Victoria  Land  and  of 
Graham's  Land,  and  reached  the  parallel  of  80°  S. 
Sir  James  Boss  was  himself  a  naturalist  of  no 
mean  acquirements,  and  Dr.  Hooker,^  the  present 
President  of  the  Boyal  Society,  accompanied  him 
as  naturalist  to  the  expedition,  so  that  the  obser- 
vations upon  the  fauna  and  flora  of  the  Antarctic 
reo^ions  made  during-  this  cruise  were  sure  to  have 
a  peculiar  value  and  importance,  even  had  not  the 
*  [Now  Sir  Joseph  Hooker.    1894.] 


Iir  EXPEDITION  OF   THE   "  CHALLENGER  "         73 

attention  of  the  voyagers  been  particularly  directed 
to  the  importance  of  noting  the  occurrence  of  the 
minutest  forms  of  animal  and  vegetable  hfe  in  the 
ocean. 

Among  the  scientific  instiiictions  for  the  voyage 
drawn  up  by  a  committee  of  the  Royal  Society, 
however,  there  is  a  remarkable  letter  from  Von 
Humboldt  to  Lord  Minto,  then  First  Lord  of  the 
Admiralty,  in  which,  among  other  things,  he 
dwells  upon  the  significance  of  the  researches  into 
the  microscopic  composition  of  rocks,  and  the  dis- 
covery of  the  great  share  which  microscopic  organ- 
isms take  in  the  formation  of  the  crust  of  the  earth 
at  the  present  day,  made  by  Ehrenberg  in  the  years 
1836-39.  Ehrenberg,  in  fact,  had  shown  that  the 
extensive  beds  of  "  rotten-stone "  or  "  TripoH  '* 
which  occur  in  various  parts  of  the  world,  and 
notably  at  Bilin  in  Bohemia,  consisted  of  accumu- 
lations of  the  silicious  cases  and  skeletons  of  Biato- 
macecB,  sponges,  and  Radiolaria ;  he  had  proved 
that  similar  deposits  were  being  formed  by 
Diatoonacem,  in  the  pools  of  the  Thiergarten  in 
Berlin  and  elsewhere,  and  had  pointed  out  that,  if 
it  were  commercially  worth  while,  rotten-stone 
might  be  manufactured  by  a  process  of  diatom- 
culture.  Observations  conducted  at  Cuxhaven  in 
1839,  had  revealed  the  existence,  at  the  surface  of 
the  waters  of  the  Baltic,  of  living  Diatoms  and 
Badiolaricb  of  the  same  species  as  those  which,  in 


74         EXPEDITION   OF   THE   "  CHALLENGER  "         m 

a  fossil  state,  constitute  extensive  rocks  of  tertiary 
age  at  Caltanisetta,  Zante,  and  Oran,  on  the 
shores  of  the  Mediterranean. 

Moreover,  in  the  fresh-water  rotten-stone  beds 
of  Bilin,  Ehrenberg  had  traced  out  the  metamor- 
phosis, effected  apparently  by  the  action  of  perco- 
lating water,  of  the  primitively  loose  and  friable 
deposit  of  organized  particles,  in  which  the  silex 
exists  in  the  hydrated  or  soluble  condition.  The 
silex,  in  fact,  undergoes  solution  and  slow  redepo- 
sition,  until,  in  ultimate  result,  the  excessively 
fine-grained  sand,  each  particle  of  which  is  a 
skeleton,  becomes  converted  into  a  dense  opaline 
stone,  with  only  here  and  there  an  indication  of  an 
organism. 

From  the  consideration  of  these  facts,  Ehren- 
berg, as  early  as  the  year  1839,  had  arrived  at  the 
conclusion  that  rocks,  altogether  similar  to  those 
which  constitute  a  large  part  of  the  crust  of  the 
earth,  must  be  forming,  at  the  present  day,  at  the 
bottom  of  the  sea  ;  and  he  threw  out  the  sugges- 
tion that  even  where  no  trace  of  organic  structure 
is  to  be  found  in  the  older  rocks,  it  inay  have  been 
lost  by  metamorphosis.^ 


^  Ucherdie  nuch  jrtzt  znUlrcich  Irheiirltt  Thicrarten  dcr  Krcide- 
hildnnq  und  den  Organisvins  der  Polythnhtmirn.  Jbhandlungen 
der  K'on.  Al'ad.  dcr  Wissnichaften.  1839.  Berlin.  1841,  I  am 
afraid  that  this  remarkable  paper  has  been  somewhat  overlooked 
in  the  recent  discussious  of  the  relation  of  ancient  rocks  to 
modern  deposits. 


Ill  EXPEDITION   OF   THE   "  CHALLENGER "       75 

The  results  of  the  Antarctic  exploration,  as 
stated  by  Dr.  Hooker  in  the  "  Botany  of  the  Ant- 
arctic Voyage,"  and  in  a  paper  which  he  read 
before  the  British  Association  in  1847,  are  of  the 
greatest  importance  in  connection  with  these 
views,  and  they  are  so  clearly  stated  in  the  former 
work,  which  is  somewhat  inaccessible,  that  I  make 
no  apology  for  quoting  them  at  length — 

*'  The  waters  and  the  ice  of  the  South  Polar  Ocean  were  alike 
fonnd  to  abound  with  microscopic  vegetables  belonging  to  the 
order  D iatomacece.  Though  much  too  small  to  be  discernible 
by  the  naked  eye,  they  occurred  in  such  countless  myriads  as 
to  stain  the  berg  and  the  pack  ice  wlierever  they  were  washed  by 
the  swell  of  the  sea  ;  and,  when  enclosed  in  the  congealing 
surface  of  the  water,  they  imparted  to  the  brash  and  pancake 
ice  a  pale  ochreous  colour.  In  the  open  ocean,  northward  of 
the  frozen  zone,  this  order,  though  no  doubt  almost  universally 
present,  generally  eludes  the  search  of  the  naturalist;  except 
when  its  species  are  congregated  amongst  that  mucous  scum 
which  is  sometimes  seen  floating  on  the  waves,  and  of  whose 
real  nature  we  are  ignorant ;  or  when  the  coloured  contents  of 
the  marine  animals  who  feed  on  these  Algse  are  examined.  To 
the  south,  however,  of  the  belt  of  ice  which  encircles  the  globe, 
between  the  parallels  of  f  0°  and  70°  S.,  and  in  the  waters  com- 
prised between  that  belt  and  the  highest  latitude  ever  attained  by 
man,  this  vegetation  is  very  conspicuous,  from  the  contrast 
between  its  colour  and  the  white  snow  and  ice  in  which  it  is 
imbedded.  Insomuch,  that  in  the  eightieth  degree,  all  the 
surface  ice  carried  along  by  the  currents,  the  sides  of  every 
berg,  and  the  base  of  the  great  Victoria  Barrier  itself,  within 
reach  of  the  swell,  were  tinged  brown,  as  if  the  polar  waters 
were  charged  with  oxide  of  iron. 

"  As  the  majority  of  these  plants  consist  of  very  simple  vege- 
table cells,  enclosed  in  indestructible  silex  (as  other  Algae  are  in 
carbonate  of  lime),  it  is  obvious  that  the  death  and  decomposi- 


76  EXPEDITION   OF   THE   "  CHALLENGER "         III 

tiou  of  such  multitudes  must  form  sedimentary  deposits,  propor- 
tionate in  their  extent  to  the  k'ngth  and  exposure  of  the  coast 
against  which  they  are  washed,  in  thickness  to  the  power  of 
such  agents  as  the  winds,  currents,  and  sea,  which  sweej) 
them  more  energetically  to  certain  positions,  and  in  purity,  to 
the  depth  of  the  water  and  nature  of  the  bottom.  Hence  we 
detected  their  remains  along  every  icebound  shore,  in  the  depths 
of  the  adjacent  ocean,  between  80  and  400  fathoms.  Off 
Victoria  Barrier  (a  jierpendicular  wall  of  ice  between  one  and 
two  hundred  feet  above  the  level  of  the  sea)  the  bottom  of  the 
ocean  was  covered  with  a  stratum  of  pure  white  or  green  mud, 
composed  principally  of  the  silicious  shells  of  the  Diatomaccce. 
These,  on  being  put  into  water,  rendered  it  cloudy  like  milk, 
and  took  many  hours  to  subside.  In  the  very  deep  water  off 
Victoria  and  Graham's  Land,  this  mud  was  particularly  pure  and 
fine  ;  but  towards  the  shallow  shores  there  existed  a  greater  or 
less  admixture  of  disintegrated  rock  and  sand  ;  so  that  the 
organic  compounds  of  the  bottom  frequently  bore  but  a  small 
proportion  to  the  inorganic."  .   .   . 

"  The  universal  existence  of  such  an  invisible  vegetation  as 
that  of  the  Antarctic  Ocean,  is  a  truly  wonderful  fact,  and  the 
more  from  its  not  being  accompanied  by  plants  of  a  high  order. 
During  the  years  we  spent  there,  I  had  been  accustomed  to 
regard  the  phenomena  of  life  as  difl'ering  totally  from  what  obtains 
throughout  all  other  latitudes,  for  everything  living  appeared 
to  be  of  animal  origin.  The  ocean  swarmed  with  Mollusca,  and 
particularly  entomostracous  Ci-uHacca,  small  whales,  and  por- 
poises ;  the  sea  abounded  with  penguins  and  seals,  and  the  air 
with  birds  ;  the  animal  kingdom  was  ever  present,  the  larger 
creatures  preying  on  the  smaller,  and  these  again  on  smaller 
still  ;  all  seemed  carnivorous.  The  herbivorous  were  not  recog- 
nised, because  feeding  on  a  microscopic  herbage,  of  whose  true 
nature  I  had  formed  an  erroneous  impression.  It  is,  therefore, 
with  no  little  satisfaction  that  I  now  class  the  Diafomacece  with 
plants,  probably  niaintainiiig  in  the  South  Polar  Ocean  that 
balance  between  the  vegetable  and  the  animal  kingdoms  whifjh 
prevails  over  the  surface  of  our  globe.  Nor  is  the  sustenance 
and  nutrition  of  the  animal  kingdom  the  only  function  these 


Ill 


EXPEDITION   OF   THE   "  CHALLENGER ''        77 


minute  productions  may  perform  ;  they  may  also  be  the  purifiers 
of  the  vitiated  atmosphere,  and  thus  execute  in  the  Antarctic 
latitudes  the  office  of  our  trees  and  grass  turf  in  the  temperate 
regions,  and  the  broad  leaves  of  the  palm,  &c.,  in  the 
tropics."  .... 

With  respect  to  the  distribution  of  tlie 
DiatGmaccm,  Dr.  Hooker  remarks  : — ■ 

**  There  is  probably  no  latitude  between  that  of  Spitzbergen 
and  Victoria  Land,  where  some  of  the  species  of  either  country 
do  not  exist :  Iceland,  Britain,  the  Mediterranean  Sea,  North  and 
South  America,  and  the  South  Sea  Islands,  all  possess  Antarctic 
Diatomacece.  The  silicious  coats  of  species  only  known  living 
in  the  waters  of  the  South  Polar  Ocean,  have,  during  past 
ages,  contriliuted  to  the  formation  of  rocks  ;  and  thus  they  out- 
live several  successive  creations  of  organized  beings.  The 
phonolite  stones  of  the  Ehine,  and  the  Tripoli  stone,  contain 
species  identical  with  Avhat  are  now  contributing  to  form  a  sedi- 
mentary deposit  (and  perhaps,  at  some  future  period,  a  bed  of 
rock)  extending  in  one  continuous  stratum  for  400  measured 
miles.  I  allude  to  the  shores  of  the  Victoria  Barrier,  along 
whose  coast  the  soundings  examined  were  invariably  charged 
with  diatomaceous  remains,  constituting  a  bank  which  stretches 
200  miles  north  from  the  base  of  Victoria  Barrier,  while  the 
average  depth  of  water  above  it  is  300  fathoms,  or  1,800  feet. 
Again,  some  of  the  Antarctic  species  have  been  detected  floating 
in  the  atmosphere  which  overhangs  the  wide  ocean  between 
Africa  and  America.  The  knowledge  of  this  marvellous  fact  we 
owe  to  Mr.  Darwin,  who,  when  he  was  at  sea  off  the  Cape  de 
Verd  Islands,  collected  an  impalpable  powder  which  fell  on 
Captain  Fitzroy's  ship.  He  transmitted  this  dust  to  Ehrenberg, 
who  ascertained  it  to  consist  of  the  silicious  coats,  chiefly  of 
American  Diatomacece,  which  were  being  wafted  through  the 
•upper  region  of  the  air,  when  some  meteorological  phenomena 
checked  them  in  their  course  and  deposited  them  on  the  ship 
and  surface  of  the  ocean. 

*'  The  existence  of  the  remains  of  many  species  of  this  order 


78  EXPEDITION   OF   THE   "  CHALLENGER  m 

(and  amongst  them  some  Antarctic  ones)  in  the  volcanic  ashes, 
pumice,  and  scoriae  of  active  and  extinct  volcanoes  (those  of  the 
Mediterranean  Sea  and  Ascension  Island,  for  instance)  is  a  fact 
hearing  immediately  upon  the  present  subject.  Mount  Erebus, 
a  volcano  12,400  feet  high,  of  the  first  class  in  dimensions  and 
energetic  action,  rises  at  once  from  the  ocean  in  the  seventy- 
eighth  degree  of  south  latitude,  and  abreast  of  the  Diatomacece 
bank,  ^vhich  reposes  in  part  on  its  base.  Hence  it  may  not 
appear  preposterous  to  conclude  that,  as  Vesuvius  receives  the 
waters  of  the  Mediterranean,  with  its  fish,  to  eject  them  by  its 
crater,  so  the  subterranean  and  subaqueous  forces  which  maintain 
Mount  Ei-ebns  in  activity  may  occasionally  receive  organic 
matter  from  the  bank,  and  disgorge  it,  together  with  those 
volcanic  products,  ashes  and  pumice. 

"Along  the  shores  of  Graham's  Land  and  the  South  Shetland 
Islands,  we  have  a  parallel  combination  of  igneous  and  aqueous 
action,  accompanied  with  an  equally  copious  supply  o^  Diatom- 
accoe.  In  the  Gulf  of  Erebus  and  Terror,  fifteen  degrees  north 
of  Victoria  Land,  and  placed  on  the  opposite  side  of  the  globe, 
the  soundings  were  of  a  similar  nature  with  those  of  the  Victoria 
Land  and  Barrier,  and  the  sea  and  ice  as  full  of  Diatomacece, 
This  was  not  only  proved  by  the  deep  sea  lead,  but  by  the 
examination  of  bergs  which,  once  stranded,  had  floated  off"  and 
become  reversed,  exposing  an  accunmlation  of  white  friable  mud 
frozen  to  their  bases,  which  abounded  with  these  vegetable 
remains. " 

The  Challenger  has  explored  the  Antarctic  seas 
in  a  region  intermediate  between  those  examined 
by  Sir  James  Ross's  expedition ;  and  the  observa- 
tions made  by  Dr.  Wyville  Thomson  and  his 
colleagues  in  every  respect  confirm  those  of  Dr. 
Hooker  :— 

"On  the  11th  of  February,  lat.  60°  52'  S.,  long.  80°  20'  E., 
and  March  3,   lat.  53°  55'  S.,  long.  108°  35'  E.,  the  sounding 


ni  EXPEDITION  OF   THE   "CHALLENGER"        79 

instrument  came  up  filled  with  a  very  fine  cream-coloured  paste, 
which  scarcely  effervesced  with  acid,  and  dried  into  a  very  lighl;, 
impalpable,  white  powder.  This,  when  examined  under  the 
microscope,  was  found  to  consist  almost  entirely  of  the  frustulea 
of  Diatoms,  some  of  them  wonderfully  perfect  in  all  the  details 
of  their  ornament,  and  many  of  them  broken  up.  The  species 
of  Diatoms  entering  into  this  deposit  have  not  yet  been  worked 
up,  but  they  appear  to  be  referable  chiefly  to  the  genera  Fragil- 
laria,  Coscinodisc^cs,  Chcctoceros,  A.^teromphahis,  and  Didyocha, 
with  fragments  of  the  separated  roils  of  a  singular  silicious 
organism,  with  which  we  were  unacquainted,  and  which  made 
up  a  large  proportion  of  the  finer  matter  of  this  deposit.  Mixed 
with  the  Diatoms  there  were  a  few  small  Glohigerince,  some  of  the 
tests  and  spicules  of  Radiolarians,  and  some  sand  particles  ;  but 
these  foreign  bodies  were  in  too  small  proportion  to  affect  the 
formation  as  consisting  practically  of  Diatoms  alone.  On  the 
4th  of  February,  in  lat.  52°,  29'  S.,  long.,  71°  36'  E.,  a  little  to 
the  north  of  the  Heard  Islands,  the  tow-net,  dragging  a  few 
fathoms  b-low  the  surface,  came  up  nearly  filled  with  a  pale  yellow 
gelatinous  mass  This  was  found  to  consist  entirely  of  Diatoms 
of  the  same  species  as  those  found  at  the  bottom.  By  far  the 
most  abundant  was  the  little  bundle  of  silicious  rods,  fastened 
together  loosely  at  one  end,  separating  from  one  another  at  the 
other  end,  and  the  whole  bundle  loosely  twisted  into  a  spindle. 
The  rods  are  hollow,  and  contain  the  characteristic  endochrome 
of  the  Diatomacece.  Like  the  Glohigcrina  ooze,  then,  which  it 
succeeds  to  the  southward  in  a  band  apparently  of  no  gi-eat 
width,  the  materials  of  this  silicious  deposit  are  derived  entirely 
from  the  surface  and  intermediate  depths.  It  is  somewhat 
singular  that  Diatoms  did  not  appear  to  be  in  such  large  num- 
ber on  the  surface  over  the  Diatom  ooze  as  they  were  a  little 
further  north.  This  may  perhaps  be  accounted  for  by  our  not 
having  struck  their  belt  of  depth  with  the  tow-net ;  or  it  is 
possible  that  when  we  found  it  on  the  11th  of  February  the  bottom 
deposit  was  really  shifted  a  little  to  the  south  by  the  warm 
current,  the  excessively  fine  flocculent  debris  of  the  Diatoms 
taking  a  certain  time  to  sink.  The  belt  of  Diatom  ooze  is 
certainly  a  little  further  to  the  southward  in  long.   83°  E.,  in 


80  EXPEDITION   OF  THE   "  CHALLENGER  '*        ni 

the  patli  of  the  reflux  of  the  Agiilhas  current,  than  in  long. 
108°  E. 

"All  along  the  edge  of  the  ice-pack — everywhere,  in  fact,  to 
the  south  of  the  two  stations— on  the  11th  of  February  on  our 
southward  voyage,  and  on  the  3rd  of  March  on  our  return,  we 
brought  up  fine  sand  and  grayish  mud,  with  small  pebbles  of 
quartz  and  felspar,  and  small  fragments  of  mica-slate,  chlorite- 
slate,  clay-slate,  gneiss,  and  granite.  This  deposit,  I  have  no 
doubt,  was  derived  from  the  surface  like  the  others,  but  in  this 
case  by  the  melting  of  icebergs  and  the  precipitation  of  foreign 
matter  contained  in  the  ice. 

"We  never  saw  any  trace  of  gravel  or  sand,  or  any  material 
necessarily  derived  from  land,  on  an  iceberg.  Several  showed 
Tertical  or  irregular  fissures  filled  with  discoloured  ice  or  snow  ; 
but,  when  looked  at  closely,  the  discoloration  proved  usually  to 
be  very  slight,  and  the  effect  at  a  distance  was  usually  due  to 
the  foreign  material  filling  the  fissure  reflecting  light  less  per- 
fectly than  the  general  surface  of  the  berg.  I  conceive  that 
the  upper  surface  of  one  of  these  great  tabular  southern  ice- 
bergs, including  by  far  the  greater  part  of  its  bulk,  and  culmin- 
ating in  the  portion  exposed  above  the  surface  of  the  sea,  was 
formed  by  the  piling  up  of  successive  layers  of  snow  during  the 
period,  amounting  perhaps  to  several  centuries,  during  which 
the  ice-cap  was  slowly  forcing  itself  over  the  low  land  and  out 
to  sea  over  a  long  extent  of  gentle  slope,  until  it  reached  a  depth 
considerably  above  200  fathoms,  when  the  lower  specific  weight 
of  the  ice  caused  an  upward  strain  which  at  length  overcame  the 
cohesion  of  the  mass,  and  portions  were  rent  off  and  floated 
away.  If  this  be  the  true  histoiy  of  the  formation  of  these 
icebergs,  the  absence  of  all  land  debris  in  the  portion  exposed 
above  tlie  surface  of  the  sea  is  readily  understood.  If  any  such 
exist,  it  must  be  confined  to  the  lower  part  of  the  berg,  to  that 
pai-t  which  has  at  one  time  or  other  moved  on  the  floor  of  the 
ice-cap. 

"  The  icebergs,  when  they  are  first  dispersed,  float  in  from 
200  to  250  fathoms.  When,  therefore,  they  have  been  drifted 
to  latitudes  of  65°  or  64°  S.,  the  bottom  of  the  berg  just  reaches 
the  layer  at  which  the  temperature  of  the  water  is  distinctly 


in  EXPEDITION   OF   THE   "CHALLENGER"         81 

rising,  and  it  is  rapidly  melted,  and  the  mud  and  pebbles  with 
which  it  i?  more  or  less  charged  are  precipitated.  That  this 
precipitation  takes  place  all  over  the  area  where  the  icebergs  are 
breaking  up,  constantly,  and  to  a  considerable  extent,  is  evident 
from  the  fact  of  the  soundings  being  entirely  composed  of  such 
deposits  ;  for  the  Diatoms,  Globu/erince,  and  radiolarians  are 
present  on  the  surface  in  large  numbers  ;  and  unless  the  deposit 
from  the  ice  were  abundant  it  would  soon  be  covered  and 
masked  by  a  layer  of  the  exuvia  of  surface  organisms." 

The  observations  wliich  have  been  detailed 
leave  no  doubt  that  the  Antarctic  sea  bottom, 
from  a  little  to  the  south  of  the  fiftieth  parallel, 
as  far  as  80''  S.,  is  being  covered  by  a  fine  deposit  of 
silicious  mud,  more  or  less  mixed,  in  some  parts, 
with  the  ice-borne  debris  of  polar  lands  and  with 
the  ejections  of  volcanoes.  The  silicious  particles 
which  constitute  this  mud,  are  derived,  in  part, 
from  the  diatomaceous  plants  and  radiolarian 
animals  which  throng  the  surface,  and,  in  part, 
from  the  spicula  of  sponges  which  live  at  the 
bottom.  The  evidence  respecting  the  correspond- 
ing Arctic  area  is  less  complete,  but  it  is  sufficient  to 
justify  the  conclusion  that  an  essentially  similar 
silicious  cap  is  being  formed  around  the  northern 
pole. 

There  is  no  doubt  that  the  constituent  particles 
of  this  mud  may  agglomerate  into  a  dense  rock, 
such  as  that  formed  at  Oran,  on  the  shores  of  the 
Mediterranean,  which  is  made  up  of  similar 
materials.  Moreover,  in  the  case  of  freshwater 
deposits  of  this  kind,  it  is  certain  that  the  action 

192 


82        EXPEDITION   OF   THE   "CHALLENGER"  m 

of  percolating  water  may  convert  the  originally 
soft  and  friable,  fine-grained  sandstone  into  a 
dense,  semi-transparent  opaline  stone,  the  silicious 
organized  skeletons  being  dissolved,  and  the  siiex 
re-deposited  in  an  amorphous  state.  Whether 
such  a  metamorphosis  as  this  occurs  in  submarine 
deposits,  as  well  as  in  those  formed  in  fresh  water, 
does  not  appear;  but  there  seems  no  reason  to 
doubt  that  it  may.  And  hence  it  may  not  be 
hazardous  to  conclude  that  very  ordinary  meta- 
morphic  agencies  may  convert  these  polar  caps  into 
a  form  of  quartzite. 

In  the  great  intermediate  zone,  occupying  some 
110°  of  latitude,  which  separates  the  circumpolar 
Arctic  and  Antarctic  areas  of  silicious  deposit,  the 
Diatoms  and  Badiolaria  of  the  surface  water  and 
the  sponges  of  the  bottom  do  not  die  out,  and,  so 
far  as  some  forms  are  concerned,  do  not  even 
appear  to  dimmish  in  total  number ;  though,  on  a 
rough  estimate,  it  would  appear  that  the  propor- 
tion of  Badiolaria  to  Diatoms  is  much  greater  than 
in  the  colder  seas.  Nevertheless  the  composition 
of  the  deep-sea  mud  of  this  intermediate  zone  is 
entirely  different  from  that  of  the  circumpolar 
regions. 

The  first  exact  information  respecting  the 
nature  of  this  mud  at  depths  greater  than  1,000 
fathoms  was  given  by  Ehrenberg,  in  the  account 
which  he  published  in  the  "  Monatsberichte "  of 


Ill 


EXPEDITION   OF   THE   "CHALLENGER"         83 


the  Berlin  Academy  for  the  year  1853,  of  the 
soundings  obtained  by  Lieut.  Berr3rtnan,  of  the 
United  States  Navy,  in  the  North  Atlantic, 
between  Newfoundland  and  the  Azores. 

Observations  which  confirm  those  of  Ehrenberg 
in  all  essential  respects  have  been  made  by 
Professor  Bailey,  myself,  Dr.  Wallich,  Dr.  Car- 
penter, and  Professor  Wyville  Thomson,  in  their 
earlier  cruises;  and  the  continuation  of  the 
Glohigerina  ooze  over  the  South  Pacific  has  been 
proved  by  the  recent  work  of  the  Challenger,  by 
which  it  is  also  shown,  for  the  first  time,  that,  in 
passing  from  the  equator  to  high  southern  lati- 
tudes, the  number  and  variety  of  the  Foramimfera 
diminishes,  and  even  the  Glchigerince  become 
dwarfed.  And  this  result,  it  will  be  observed,  is 
in  entire  accordance  with  the  fact  already  men- 
tioned that,  in  the  sea  of  Kamschatka,  the  deep- 
sea  mud  was  found  by  Bailey  to  contain  no  cal- 
careous organisms. 

Thus,  in  the  whole  of  the  "  intermediate  zone," 
the  silicious  deposit  which  is  being  formed  there, 
as  elsewhere,  by  the  .accumulation  of  sponge- 
spicula,  Radiolaria,  and  Diatoms,  is  obscured  and 
overpowered  by  the  immensely  greater  amount  of 
calcareous  sediment,  which  arises  fi:om  the  ags^re- 
gation  of  the  skeletons  of  dead  Foraminifera.  The 
similarity  of  the  deposit,  thus  composed  of  a 
large  percentage  of  carbonate  of  lime,  and  a  small 
percentage  of  silex,  to  chalk,  regarded  merely  as  a 


84    EXPEDITION  OF  THE  "  CHALLENGER  "    m 

kind  of  rock,  whicli  Avas  first  pointed  out  by 
Ehrenberg,^  is  now  admitted  on  all  bands ;  nor 
can  it  be  reasonably  doubted,  that  ordinary  meta- 
morphic  agencies  are  competent  to  convert  the 
"  modern  chalk  "  into  hard  limestone  or  even  into 
crystalline  marble. 

Ehrenberg  appears  to  have  taken  it  for  granted 
that  the' Glohigcrince  and  other  Fcraminifcra  which 
are  found  in  the  deep-sea  mud,  live  at  the  gi'eat 
depths  in  which  their  remains  are  found  ;  and  he 
supports  this  opinion  by  producing  evidence  that 
the  soft  parts  of  these  organisms  are  preserved, 
and  may  be  demonstrated  by  removing  the  cal- 
careous matter  with  dilute  acids.     In  1857,  the 

^  The  following  passages  in  Elirenberg's  memoir  ob  The 
Organis'ms  in  the  Chalk  which  are  still  living  (1839),  are  con- 
clusive : — 

* '  7.  The  dawning  period  of  the  existing  living  organic  creation, 
if  such  a  period  is  distinguishable  (which  is  doubtful),  can  only 
be  supposed  to  have  existed  on  the  other  side  of,  and  below,  the 
chalk  formation  ;  and  thus,  either  the  chalk,  with  its  wide- 
spread and  thick  beds,  must  enter  into  the  series  of  newer 
formations  ;  or  some  of  the  accepted  four  great  geological  periods, 
the  quaternary,  teitiary,  and  secondary  formations,  contain 
organisms  which  still  live.  It  is  more  probable,  in  the  propor- 
tion of  3  to  1,  that  the  transition  or  primary  period  is  not 
different,  but  that  it  is  only  more  difficult  to  examine  and 
understand,  by  reason  of  the  gradual  and  prolonged  chemical 
decomposition  and  metamorphosis  of  many  of  its  organic 
constitttents." 

"10.  By  the  mass-forming  Infusoria  and  Polythalamia, 
secondary  are  not  distinguishable  from  tertiary  formations  ;  and, 
from  what  has  been  said,  it  is  possible  that,  at  this  very  day, 
rock  masses  are  forming  in  the  sea,  and  being  raised  by  volcanic 
agencies,  the  constitution  of  which,  on  the  whole,  is  altogether 
similar  to  that  of  the  chalk.  The  chalk  remains  distinguishable 
by  its  organic  remains  as  a  formation,  btit  not  as  a  kind  of 
rock." 


Ill 


EXPEDITION   OF   THE  "CHALLENGER*'         85 


evidence  for  and  against  this  conclusion  appeared 
to  me  to  be  insufficient  to  warrant  a  positive  con- 
clusion one  way  or  the  other,  and  I  expressed 
myself  in  my  report  to  the  Admiralty  on  Captain 
Da3nnan's  soundings  in  the  following  terms : — 

"  When  we  consider  the  immense  area  over  which  this 
deposit  is  spread,  the  de[)th  at  which  its  formation  is  going  on, 
and  its  similarity  to  chalk,  and  still  more  to  such  rocks  as  the 
marls  of  Caltanisetta,  the  question,  whence  are  all  these  organ- 
isms derived  ?  becomes  one  of  high  scientific  interest. 

"Three  answers  have  suggested  themselves  : — 

"  In  accordance  with  the  prevalent  view  of  the  limitation  of 
life  to  comparatively  small  depths,  it  is  imagined  either  :  1,  that 
these  organisms  have  drifted  into  their  present  position  from 
shallower  waters  ;  or  2,  that  they  habitually  live  at  the  surface 
of  the  ocean,  and  only  fall  down  into  their  present  position. 

**  1.  I  conceive  that  the  first  supposition  is  negatived  by  the 
extremely  marked  zoological  peculiarity  of  the  deep-sea  fauna. 

"  Had  the  Globigerince  been  drifted  into  their  present  position 
from  shallow  water,  we  should  find  a  very  large  proportion  of 
the  characteristic  inhabitants  of  shallow  watei-s  mixed  with 
them,  and  this  would  the  more  certainly  be  the  case,  as  the 
large  Globigerince,  so  abundant  in  the  deep-sea  soundings,  are, 
in  proportion  to  their  size,  more  solid  and  massive  than  almost 
any  other  Fcraminifcra.  But  the  fact  is  that  the  proportion  of 
other  Fornminifera  is  exceedingly  small,  nor  have  I  found  as 
yet.,  in  the  deep-sea  deposits,  any  such  matters  as  fragments 
of  molluscous  shells,  oi  Echini,  &c.,  which  abound  in  shallow 
waters,  and  are  quite  as  likely  to  be  drifted  as  the  heavy  Glohi- 
gerince.  Again,  the  relative  proportions  of  young  and  fully 
formed  Globigerince  seem  inconsistent  with  the  notion  that  they 
have  travelled  far.  And  it  seems  difficult  to  imagine  why,  had 
the  deposit  been  accumulated  in  this  way,  Coscinodisci  should 
so  almost  entirely  represent  the  Diatomacece. 

"2.  The  second  hypothesis  is  far  more  feasible,  and  is 
strongly  supported  by  the  fact  that  many  Polifcisti7iece[Radicla' 


86        EXPEDITION   OF   THE   "  CHALLENGER  "  in 

ria]  and  Coseinodisci  are  well  known  to  live  at  the  surface  of  the 
ocean.  Mr.  Macdonald,  Assistant-Surgeon  of  H.M.S.  Herald, 
now  in  the  South- Western  Pacific,  has  lately  sent  home  some 
very  valuable  observations  on  living  forms  of  this  kind,  met 
with  in  the  stomachs  of  oceanic  mollusks,  and  therefore  certainly 
inhabitants  of  the  superficial  layer  of  the  ocean.  But  it  is  a 
singular  circumstance  that  only  one  of  the  forms  figured  by  Mr. 
Macdonald  is  at  all  like  a  Glohigerina,  and  there  are  some 
peculiarities  about  even  this  which  make  me  greatly  doubt  its 
affinity  with  that  genus.  The  form,  indeed,  is  not  unlike 
that  of  a  Glohigerina,  but  it  is  provided  with  long  radiating 
processes,  of  which  I  have  never  seen  any  trace  in  Glohigerina. 
Did  they  exist,  they  might  explain  what  otherwise  is  a  great 
objection  to  this  view,  viz. ,  how  is  it  conceivable  that  the  heavy 
Glohigerina  should  maintain  itself  at  the  surface  of  the 
water  ? 

"  If  the  organic  bodies  in  the  deep-sea  soundings  have  neither 
been  drifted,  nor  have  fallen  from  above,  there  remains  but  one 
alternative — they  must  have  lived  and  died  where  they  are. 

*'  Important  objections,  however,  at  once  suggest  themselves 
to  this  view.  How  can  animal  life  be  conceived  to  exist 
under  such  conditions  of  light,  temperature,  pressure,  and 
aeration  as  must  obtain  at  these  vast  depths  ? 

"  To  this  one  can  only  reply  that  we  know  for  a  certainty 
that  even  very  highly-organized  animals  do  continue  to  live  at 
a  depth  of  300  and  400  fathoms,  inasmuch  as  they  have  been 
dredged  up  thence  ;  and  that  the  diflference  in  the  amount  of 
light  and  heat  at  400  and  at  2,000  fathoms  is  probably,  so  to 
speak,  very  far  less  than  the  diff"erence  in  complexity  of  organi- 
sation between  these  animals  and  the  humbler  Protozoa  and 
Protophyta  of  the  deep-sea  soundings. 

"  I  confess,  though  as  yet  far  from  regarding  it  proved  that 
the  Glohigerinoi  live  at  these  depths,  the  balance  of  probabilities 
saems  to  me  to  incline  in  that  direction.  And  there  is  one 
circumstance  which  weighs  strongly  in  my  mind.  It  may  be 
taken  as  a  law  that  any  genus  of  animals  which  is  found  far 
back  in  time  is  capable  of  living  under  a  great  variety  of  circum- 
stances as  regards  light,  temperature,  and  pressure.     Now,  the 


Ill  EXPEDITION   OF   THE   "CHALLENGER"        87 

genus  Glohigerina  is  abundantly  represented  in  the  cretaceous 
epoch,  and  perhaps  earlier. 

"1  abstain,  however,  at  present  from  drawing  any  positive 
conclusions,  preferring  rather  to  await  the  result  of  more 
extended  observations."  ^ 

Dr.  Wallich,  Professor  Wyville  Thomson,  and 
Dr.  Carpenter  concluded  that  the  Glchigei^inm  hve 
at  the  bottom.  Dr.  WalHch  writes  in  1862—"  By 
sinking  very  fine  gauze  nets  to  considerable  depths, 
I  have  repeatedly  satisfied  myself  that  Glchigerina 
does  not  occur  in  the  superficial  strata  of  the 
ocean."  "^  Moreover,  having  obtained  certain  living 
star-fish  from  a  depth  of  1,260  fathoms,  and  found 
their  stomachs  full  of  "  fresh-looking  Glohigerince  " 
and  their  ddhris — he  adduces  this  fact  in  support 
of  his  belief  that  the  Glohigerina^  live  at  the 
bottom. 

On  the  other  hand,  MuUer,  Haeckel,  Major 
O.ven,  Mr.  Gwyn  Jeffries,  and  other  observers, 
found  that  Glohigerinx,  with  the  allied  genera 
Orhidina  and  Fidvimdina,  sometimes  occur  abund- 
antly at  the  surface  of  the  sea,  the  shells  of  these 
pelagic  forms  being  not  unfrequently  provided 
with  the  long  spines  noticed  by  Macdonald ;  and 
in  1865  and  1866,  Major  Owen  more  especially 
insisted  on  the  importance  of  this  fact.  The 
recent  work  of  the  Challenger  fully  confirms  Major 
Owen's  statement.      In  the  paper  recently  pub- 

^  Appendix  to  Report  on  Deep-sea  Soundings  in  the  Atlantic 
Ocean,  by  Lieut. -Commander  Joseph  Dayman.     1857. 
-  The  No}'th  Atlantic  Sea  bed,  p.  137. 


88         EXPEDITION   OF   THE   "CHALLENGER"  III 

lished  in  the  proceedings  of  the  Royal  Society,^ 
from  which  a  quotation  has  already  been  made, 
Professor  Wyville  Thomson  says  : — 

"  I  had  formed  and  expressed  a  very  strong  opinion  on  the 
matter.  It  seemed  to  me  that  the  evidence  was  conclusive  that 
the  Foraminifera  which  formed  the  Globigcrma  ooze  lived  on 
the  bottom,  and  that  the  occurrence  of  individuals  on  the  surface 
was  accidental  and  exceptional ;  but  after  going  into  the  thing 
carefully,  and  considering  the  mass  of  evidence  which  has  been 
accumulated  by  Mr.  Murray,  I  now  admit  that  I  was  in  error  ; 
and  I  agree  with  him  that  it  may  be  taken  as  proved  that  all 
the  materials  of  such  deposits,  with  the  exception,  of  course,  of 
the  remains  of  animals  which  we  now  know  to  live  at  the 
bottom  at  all  depths,  which  occur  in  the  deposit  as  foreign 
bodies,  are  derived  from  the  surface. 

"Mr.  Murray  has  combined  with  a  careful  examination  of  the 
sounding's  a  constant  use  of  the  tow  net,  usually  at  the  surface, 
but  also  at  depths  of  from  ten  to  one  hundred  fathoms  ;  and  he 
hnds  the  closest  relation  to  exist  between  the  surface  fauna  of 
any  particular  locality  and  the  deposit  which  is  taking  place  at 
the  bottom.  In  all  seas,  from  the  equator  to  the  polar  ice,  the 
tow-net  contains  Globigtrince.  They  are  more  abundant  and  of 
a  larger  size  in  warmer  seas  ;  several  varieties,  attaining  a  large 
size  and  presenting  marked  varietal  characters,  are  found  in  the 
intertropical  area  of  the  Atlantic.  In  the  latitude  of  Kerguelen 
they  are  less  numerous  and  smaller,  while  further  south  they  are 
still  more  dwarfed,  and  only  one  variety,  the  typical  Glohigcrina 
hulloides,  is  represented.  The  living  Glohigcrince  from  the  tow- 
net  are  singularly  different  in  appearance  from  the  dead  shells 
we  find  at  the  bottom.  The  shell  is  clear  and  transparent,  and 
each  of  the  pores  which  penetrate  it  is  surrounded  by  a  raised 
crest,  the  crest  round  adjacent  pores  coalescing  into  a  roughly 

1  "Preliminary  Notes  on  the  Nature  of  the  Sea-bottom  pro- 
cured by  the  soundings  of  H.M.S.  Challenger  during  her  cruise 
in  the  Southern  Seas,  in  the  early  pait  of  the  year  1874."— 
Froceedings  of  the  lloyal  Society,  Nov,  26,  1874. 


m  EXPEDITION   OF   THE   "CHALLENGER"         89 

hexagonal  network,  so  that  the  pores  appear  to  lie  at  the 
bottom  of  a  hexagonal  pit.  At  each  angle  of  this  hexagon  the 
crest  gives  off  a  delicate  flexible  calcareous  spine,  which  is  some- 
times four  or  five  times  the  diameter  of  the  shell  in  length. 
The  spines  radiate  symmetrically  from  the  direction  of  the 
centre  of  each  chamber  of  the  shell,  and  the  sheaves  of  long 
transparent  needles  crossing  one  another  in  different  directions 
have  a  very  beautiful  effect.  The  smaller  inner  chambers  of  the 
shell  are  entirely  filled  with  an  orange-yellow  granular  sarcode  ; 
and  the  large  terminal  chamber  usually  contains  only  a  small 
irregular  mass,  or  two  or  three  small  masses  run  together,  of 
the  same  yellow  sarcode  stuck  against  one  side,  the  remainder  of 
the  chamber  being  empty.  No  definite  arrangement  and  no 
approach  to  structure  was  observed  in  the  sarcode,  and  no 
differentiation,  with  the  exception  of  round  bright-yellow  oil- 
globules,  very  much  like  those  found  in  some  of  the  radiolarians, 
which  are  scattered,  apparently  iiregularly,  in  the  sarcode.  We 
never  have  been  able  to  detect,  in  any  of  the  large  number  of 
Glohigerince  which  we  have  examined,  the  least  trace  of  pseudo- 
podia,  or  any  extension,  in  any  form,  of  the  sarcode  beyond  the 
shell. 

"In  specimens  taken  with  the  tow-net  the  spines  are  very 
usually  absent ;  but  that  is  probably  on  account  of  their  extreme 
tenuity  ;  they  are  broken  off  by  the  slightest  touch.  In  fresh 
examples  from  the  surface,  the  dots  indicating  the  oiigin  of  the 
lost  spines  may  almost  always  be  made  out  with  a  high  power. 
There  are  never  sjiines  on  the  Glohigerince  from  the  bottom, 
even  in  the  shallowest  water." 


There  can  now  be  no  douht,  therefore,  that 
Glohigerince  live  at  the  top  of  the  sea ;  but  the 
question  may  still  be  raised  whether  they  do  not 
also  live  at  the  bottom.  In  favour  of  this  view,  it 
has  been  urged  that  the  shells  of  the  Glohigerince 
of  the  surface  never  possess  such  thick  walls  as 


90        EXPEDITION   OF   THE   "  CHALLENGER"         ill 

those  which  are  found  at  the  bottom,  but  I  confess 
that  I  doubt  the  accuracy  of  this  statement. 
Again,  the  occurrence  of  minute  Glohigerince  in  all 
stages  of  development,  at  the  gToatest  depths,  is 
brought  forward  as  evidence  that  they  live  in  situ. 
But  considering  the  extent  to  which  the  surface 
organisms  are  devoured,  without  discrimination  of 
young  and  old,  by  Salpce  and  the  like,  it  is  not 
wonderful  that  shells  of  all  ages  should  be  among 
the  rejectamenta.  Nor  can  the  presence  of  the 
soft  parts  of  the  body  in  the  shells  which  form 
the  Glohigerina  ooze,  and  the  fact,  if  it  be  one, 
that  animals  living  at  the  bottom  use  them  as 
food,  be  considered  as  conclusive  evidence  that 
the  Glohigerince  live  at  the  bottom.  Such  as  die 
at  the  surface,  and  even  many  of  those  which  are 
swallowed  by  other  animals,  may  retain  much  of 
their  protoplasmic  matter  when  they  reach  the 
depths  at  which  the  temperature  sinks  to  34°  or 
32°  Fahrenheit,  where  decomposition  must  become 
exceedingly  slow. 

Another  consideration  appears  to  me  to  be  in 
favour  of  the  view  that  the  Glohigerince  and  their 
allies  are  essentially  surface  animals.  This  is  the 
fact  brought  out  by  the  Challenger  s  work,  that 
they  have  a  southern  limit  of  distribution,  which 
can  hardly  depend  upon  anything  but  the  tem- 
perature of  the  surface  water.  And  it  is  to 
be  remarked  that  this  southern  limit  occurs  at  a 
lower  latitude  in  the  Antarctic  seas  than  it  does 


ni  EXPEDITION   OF   THE   ''  CHALLENGER  "        91 

in  tlie  North  Atlantic.  According  to  Dr.  Wallicli 
("  The  North  Atlantic  Sea  Bed,"  p.  157)  Glohi- 
gerina  is  the  prevailing  form  in  the  deposits 
between  the  Faroe  Islands  and  Iceland,  and  be- 
tween Iceland  and  East  Greenland — or,  in  other 
words,  in  a  region  of  the  sea-bottom  which  lies 
altogether  north  of  the  parallel  of  60°  N. ;  while 
in  the  southern  seas,  the  Glohigerince  become 
dwarfed  and  almost  disappear  between  50^  and 
55°  S.  On  the  other  hand,  in  the  sea  of 
Kamschatka,  the  GlohigerincB  have  vanished  in 
56°  N.,  so  that  the  persistence  of  the  GloMgerina 
0')ze  in  high  latitudes,  in  the  North  Atlantic, 
would  seem  to  depend  on  the  northward  curve  of 
the  isothermals  peculiar  to  this  region ;  and  it  is 
difficult  to  understand  how  the  formation  of 
Glchigerina  ooze  can  be  affected  by  this  climatal 
peculiarity  unless  it  be  effected  by  surface  animals. 
Whatever  may  be  the  mode  of  life  of  the 
Foraminifera,  to  which  the  calcareous  element  of 
the  deep-sea  "  chalk  "  owes  its  existence,  the  fact 
that  it  is  the  chief  and  most  widely  spread 
material  of  the  sea-bottom  in  the  intermediate 
zone,  throughout  both  the  Atlantic  and  Pacific 
Oceans,  and  the  Indian  Ocean,  at  depths  from  a 
few  hundred  to  over  two  thousand  fathoms,  is 
established.  But  it  is  not  the  only  extensive 
deposit  which  is  now  taking  place.  In  1853, 
Count  Pourtales,  an  officer  of  the  United  States 
Coast   Survey,   which    has    done    so    much    for 


92        EXPEDITION   OF   THE   "  CHALLENGER  "  m 

scientific  hydrography,  observed,  that  the  mud 
forming  the  sea-bottom  at  depths  of  one  hundred 
and  fifty  fathoms,  in  31°  32'  N,  79°  35'  W.,  off 
the  Coast  of  Florida,  was  "  a  mixture,  in  about 
equal  proportions,  of  Glohigerince  and  black  sand, 
probably  greensand,  as  it  makes  a  green  mark 
when  crushed  on  paper."  Professor  Bailey, 
examining  these  grains  microscopically,  found 
that  they  were  casts  of  the  interior  cavities  of 
Foraminifera,  consisting  of  a  mineral  known  as 
Glauconite,  which  is  a  silicate  of  iron  and  alumina. 
In  these  casts  the  minutest  cavities  and  finest 
tubes  in  the  Foraminifer  were  sometimes  repro- 
duced in  solid  counterparts  of  the  glassy  mineral, 
while  the  calcareous  original  had  been  entirely 
dissolved  away. 

Contemporaneously  with  these  observations, 
the  indefatigable  Ehrenberg  had  discovered  that 
the  "greensands"  of  the  geologist  were  largely 
made  up  of  casts  of  a  similar  character,  and  proved 
the  existence  of  Foraminifera  at  a  very  ancient 
geological  epoch,  by  discovering  such  casts  in  a 
greensand  of  Lower  Silurian  age,  which  occurs 
near  St.  Petersburg. 

Subsequently,  Messrs  Parker  and  Jones  dis- 
covered similar  casts  in  process  of  formation,  the 
original  shell  not  having  disappeared,  in  specimens 
of  the  sea-bottom  of  the  Australian  seas,  brought 
home  by  the  late  Professor  Jukes.  And  the 
Challenger  has  observed   a   deposit   of  a  similar 


Ill  EXPEDITION   OF   THE   "CHALLENGER"         93 

character  in  the  course  of  the  Agulhas  current, 
near  the  Cape  of  Good  Hope,  and  in  some  othei 
locaHties  not  yet  defined. 

It  would  appear  that  this  infiltration  of  Fora- 
minifera  shells  with  Glauconite  does  not  take  place 
at  great  depths,  but  rather  in  what  may  be 
termed  a  sublittoral  region,  ranging  from  a 
hundred  to  three  hundred  fathoms.  It  cannot  be 
ascribed  to  any  local  cause,  for  it  takes  place,  not 
only  over  large  areas  in  the  Gulf  of  Mexico  and 
the  Coast  of  Florida,  but  in  the  South  Atlantic 
and  in  the  Pacific.  But  what  are  the  conditions 
which  determine  its  occurrence,  and  whence  the 
silex,  the  iron,  and  the  alumina  (with  perhaps 
potash  and  some  •  other  ingredients  in  small 
quantity)  of  which  the  Glauconite  is  composed, 
proceed,  is  a  point  on  which  no  light  has  yet  been 
thrown.  For  the  present  we  must  be  content 
with  the  fact  that,  in  certain  areas  of  the 
"  intermediate  zone,"  greensand  is  replacing  and 
representing  the  primitively  calcareo-silicious 
ooze. 

The  investigation  of  the  deposits  which  are 
now  being  formed  in  the  basin  of  the  Mediterra- 
nean, by  the  late  Professor  Edward  Forbes,  by 
Professor  Williamson,  and  more  recently  by  Dr. 
Carpenter,  and  a  comparison  of  the  results  thus 
obtained  with  what  is  known  of  the  surface  fauna, 
have  brought  to  light  the  remarkable  fact,  that 
while  the  surface  and  the  shallows  abound  with 


94        EXPEDITION   OF   THE   "CHALLENGER*"  m 

Foraminifera  and  other  calcareous  shelled  organ- 
isms, the  indications  of  life  become  scanty  at 
depths  beyond  500  or  600  fathoms,  while  almost 
all  traces  of  it  disappear  at  greater  depths,  and  at 
1,000  to  2,000  fathoms  the  bottom  is  covered  with 
a  fine  clay. 

Dr.  Carpenter  has  discussed  the  significance  of 
this  remarkable  fact,  and  he  is  disposed  to  attri- 
bute the  absence  of  life  at  great  depths,  partly 
to  the  absence  of  any  circulation  of  the  water  of 
the  Mediterranean  at  such  depths,  and  partly  to 
the  exhaustion  of  the  oxygen  of  the  water  by  the 
organic  matter  contained  in  the  fine  clay,  which 
he  conceives  to  be  formed  by  the  finest  particles 
of  the  mud  brought  down  by  the  rivers  which 
flow  into  the  Mediterranean. 

However  this  may  be,  the  explanation  thus 
offered  of  the  presence  of  the  fine  mud,  and  of  the 
absence  of  organisms  which  ordinarily  live  at  the 
bottom,  does  not  account  for  the  absence  of 
the  skeletons  of  the  organisms  which  undoubtedly 
abound  at  the  surface  of  the  Mediterranean ;  and 
it  would  seem  to  have  no  application  to  the  re- 
markable fact  discovered  by  the  Challenger,  that 
in  the  open  Atlantic  and  Pacific  Oceans,  in  the 
midst  of  the  great  intermediate  zone,  and 
thousands  of  miles  away  from  the  embouchure  of 
any  river,  the  sea-bottom,  at  depths  approaching 
to  and  beyond  3,000  fathoms,  no  longer  consists  of 
GloUgerina  ooze,  but  of  an  excessively  fine  red  clay. 


in  EXPEDITION   OF   THE   "CHALLENGER'*        95 

Professor  Thomson  gives  the  following  account 
of  this  capital  discovery  : — 

"  According  to  our  present  experience,  the  deposit  of  Glohi- 
gerina  ooze  is  limited  to  water  of  a  certain  depth,  the  extreme 
limit  of  the  pure  characteristic  formation  being  placed  at  a  depth 
of  somewhere  about  2,250  fathoms.  Crossing  from  these  shal- 
lower regions  occupied  by  the  ooze  into  deeper  soundings,  we 
find,  universally,  that  the  calcareous  formation  gradually  passes 
into,  and  is  finally  replaced  by,  an  extremely  fine  pure  clay, 
which  occupies,  speaking  generally,  all  depths  below  2,500 
fathoms,  and  consists  almost  entirely  of  a  silicate  of  the  red 
oxide  of  iron  and  alumina.  The  transition  is  very  slow,  and 
extends  over  several  hundred  fathoms  of  increasing  depth  ;  the 
shells  gradually  lose  their  sharpness  of  outline,  and  assume  a 
kind  of '  rotten  '  look  and  a  brownish  colour,  and  become  more 
and  more  mixed  with  a  fine  amorphous  red- brown  powder, 
which  increases  steadily  in  proportion  until  the  lime  has  almost 
entirely  disappeared.  This  brown  matter  is  in  the  finest  possible 
state  of  subdivision,  so  fine  that  when,  after  sifting  it  to  separate 
any  organisms  it  might  contain,  we  put  it  into  jars  to  settle,  it 
remained  for  days  in  suspension,  giving  the  water  very  much 
the  appearance  and  colour  of  chocolate. 

*'  In  indicating  the  nature  of  the  bottom  on  the  charts,  we 
came,  from  experience  and  without  any  theoretical  considera- 
tions, to  use  three  terms  for  soundings  in  deep  water.  Two  of 
these,  Gl.  oz.  and  r.  cl.,  were  very  definite,  and  indicated 
strongly-marked  formations,  with  apparently  but  few  characters 
in  common  ;  but  we  frequently  got  soundings  which  we  could 
not  exactly  call  '  Glohigerina  ooze '  or  '  red  clay, '  and  before  we 
were  fully  aware  of  the  nature  of  these,  we  were  in  the  habit  of 
indicating  them  as  '  grey  ooze '  (gr.  oz. )  We  now  recognise  the 
'  grey  ooze '  as  an  intermediate  stage  between  the  Glohigerina 
ooze  and  the  red  clay  ;  we  find  that  on  one  side,  as  it  were,  of 
an  ideal  line,  the  red  clay  contains  more  and  more  cf  the  material 
of  the  calcareous  ooze,  while  on  the  other,  the  ooze  is  mixed 
with  an  increasing  proportion  of  'red  clay.' 


96        EXPEDITION   OF   THE   "CHALLENGER  m 

"  Although  we  have  met  with  the  same  phenomenon  so 
frequently,  that  we  were  at  length  able  to  predict  the  nature  of 
the  bottom  from  the  depth  of  the  soundings  with  absolute  cer- 
tainty for  the  Atlantic  and  the  Southern  Sea,  we  had,  perhaps, 
the  best  opportunity  of  observing  it  in  our  first  section  across 
'tlie  Atlantic,  between  Teneriffe  and  St.  Thomas.  The  first  four 
stations  on  this  section,  at  depths  from  1,525  to  2,220  fathoms, 
show  Gluhigeriva  ooze.  From  the  last  of  these,  which  is  about 
300  miles  from  Teneriffe,  the  depth  gradually  increases  to  2,740 
fathoms  at  500,  and  2,950  fathoms  at  750  miles  from  Teneriffe 
The  bottom  in  these  two  soundings  might  have  been  called 
*  grey  ooze,'  for  although  its  nature  has  altered  entirely  from  the 
Glohigerina  ooze,  the  red  clay  into  which  it  is  rapidly  j)assing 
still  contains  a  considerable  admixture  of  carbonate  of  lime. 

"  The  depth  goes  on  increasing  to  a  distance  of  1,150  miles 
from  Teneriffe,  when  it  reaches  3,150  fathoms  ;  there  the  clay 
is  pure  and  smooth,  and  contains  scarcely  a  trace  of  lime.  From 
this  great  depth  the  bottom  gradually  rises,  and,  with  decreas- 
ing depth,  the  grey  colour  and  the  calcareous  composition  of  the 
ooze  return.  Three  soundings  in  2,050,  1,900,  and  1,950  fathoms 
on  the  '  Dolphin  Rise '  gave  highly  characteristic  examples  of 
the  Glohigerina  formation.  Passing  from  the  middle  plateau  of 
the  Atlantic  into  the  western  trough,  with  depths  a  little  over 
3,000  fathoms,  the  red  clay  returned  in  all  its  purity  ;  and  our 
last  sounding,  in  1,420  fathoms,  before  reaching  Sombrero, 
restored  the  Glohigerina  ooze  with  its  peculiar  associated  fauna. 

"This  section  shows  also  the  wide  extension  and  the  vast 
geological  importance  of  the  red  clay  formation.  The  total 
distance  from  Teneriffe  to  Sombrero  is  about  2,700  miles.  Pro- 
ceeding from  east  to  west,  we  have — 

About     80  miles  of  volcanic  mud  and  sand. 


„       350 

Glohigerina  ooze, 

„    1,050 

red  clay, 

„       330 

Glohigerina  ooze, 

■    „       850 

red  clay. 

40 

Glohigerina  ooze  ; 

giving  a  total  of  1,900  miles  of  red  clay  to  720  miles  of  GlohU 

gerina  ooze. 

til         EXPEDITION   OF   THE   "  CHALLENGER  "         97 

**  The  nature  and  origin  of  this  vast  deposit  of  clay  is  a  ques- 
tion of  the  very  greatest  interest ;  and  although  I  think  there 
can  be  no  doubt  that  it  is  in  the  main  solved,  yet  some  matters 
of  detail  are  still  involved  in  difficulty.  My  first  impression 
was  that  it  might  be  the  most  minutely  divided  material,  the 
ultimate  sediment  produced  by  the  disintegration  of  the  land, 
by  rivers  and  by  the  action  of  the  sea  on  exposed  coasts,  and 
held  in  suspension  and  distributed  by  ocean  currents,  and  only 
making  itself  manifest  in  places  unoccupied  by  the  Globigerina 
ooze.  Several  circumstances  seemed,  however,  to  negative  this 
mode  of  origin.  The  formation  seemed  too  uniform  :  wherever 
we  met  with  it,  it  had  the  same  character,  and  it  only  varied  in 
composition  in  containing  less  or  more  carbonate  of  lime. 

"Again,  we  were  gradually  becoming  more  and  more  con- 
vinced that  all  the  important  elements  of  the  Globigerina  ooze 
lived  on  the  surface,  and  it  seemed  evident  that,  so  long  as  the 
condition  on  the  surface  remained  the  same,  no  alteration  of 
contour  at  the  bottom  could  possibly  prevent  its  accumulation  ; 
and  the  surface  conditions  in  the  Mid -Atlantic  were  very 
uniform,  a  moderate  current  of  a  very  equal  temperature  passing 
continuously  over  elevations  and  depressions,  and  everywhere 
yielding  to  the  tow-net  the  ooze-forming  Foraniinifera  in  the 
same  proportion.  The  Mid-Atlantic  swarms  with  pelagic 
Mollusca,  and,  in  moderate  depths,  the  shells  of  these  are  con- 
stantly mixed  with  the  Globigerina  ooze,  sometimes  in  number 
sufficient  to  make  up  a  considerable  portion  of  its  bulk.  It  is 
clear  that  these  shells  must  fall  in  equal  numbers  upon  the  red 
clay,  but  scarcely  a  trace  of  one  of  them  is  ever  brought  up  by 
the  dredge  on  the  red  clay  area.  It  might  be  possible  to  explain 
the  absence  of  shell-secreting  animals  living  on  the  bottom,  on 
the  supposition  that  the  nature  of  the  deposit  was  injurious  to 
them  ;  but  then  the  idea  of  a  current  suflSciently  strong  to 
sweep  them  away  is  negatived  by  the  extreme  fineness  of  the* 
sediment  which  is  being  laid  doAvn  ;  the  absence  of  surface 
shells  appears  to  be  intelligible  only  on  the  supposition  that  they 
are  in  some  way  removed, 

"We  conclude,  therefore,  that  the  'red  clay'  is  not  an  addi- 
tional substance  introduced  from  without,  and  occupying  certain 

193 


98        EXPEDITION   OF   THE   "CHALLENGER"  m 

depressed  regions  on  account  of  some  law  regulating  its  deposi- 
tion, but  that  it  is  produced  by  the  removal,  by  some  means  or 
other,  over  these  areas,  of  the  carbonate  of  lime,  which  forms 
probably  about  98  per  cent,  of  the  material  of  the  Globigerina 
ooze.  We  can  trace,  indeed,  every  successive  stage  in  the 
removal  of  the  carbonate  of  lime  in  descending  the  slope  of  the 
ridge  or  plateau  where  the  Globigerina  ooze  is  forming,  to 
the  region  of  the  clay.  We  find,  first,  that  the  shells  of 
pteropods  and  other  surface  Mollusca  which  are  constantly 
falling  on  the  bottom,  are  absent,  or,  if  a  few  remain,  they 
are  brittle  and  yellow,  and  evidently  decaying  rapidly.  These 
shells  of  Mollusca  decompose  more  easily  and  disappear  sooner 
than  the  smaller,  and  apparently  more  delicate,  shells  of 
rhizopods.  The  smaller  Foraminifera  now  give  way,  and  are 
found  in  lessening  proportion  to  the  larger  ;  the  coccoliths  first 
lose  their  thin  outer  border  and  then  disappear  ;  and  the  clubs 
of  the  rhabdoliths  get  worn  out  of  shape,  and  are  last  seen, 
under  a  high  power,  as  infinitely  minute  cylinders  scattered  over 
the  field.  The  larger  Foraminifera  are  attacked,  and  instead 
of  being  vividly  white  and  delicately  sculptured,  they  become 
brown  and  worn,  and  finally  they  break  up,  each  according  to 
its  fashion  ;  the  chamber-walls  of  Globigerina  fall  into  wedge- 
shaped  pieces,  wliich  qixickly  disappear,  and  a  thick  rough  crust 
breaks  away  from  the  surface  of  Orbulina,  leaving  a  thin  inner 
sphere,  at  first  beautifully  transparent,  but  soon  becoming 
opaque  and  crumbling  away. 

"In  the  meantime  the  proportion  of  the  amorphous  'red 
clay'  to  the  calcareous  elements  of  all  kinds  increases,  until 
the  latter  disappear,  with  the  exception  of  a  few  scattered  shells 
of  the  larger  Foraminifera,  which  are  still  found  even  in  the 
most  characteristic  samples  of  the  'red  clay.' 

"There  seems  to  be  no  room  left  for  doubt  that  the  red  clay 
is  essentially  the  insoluble  residue,  the  ash,  as  it  were,  of  the 
calcareous  organisms  which  form  the  Globigerina  ooze,  after  the 
calcareous  matter  has  been  by  some  means  removed.  An 
ordinary  mixture  of  calcareous  Foraminifera  with  the  shells  of 
pteropods,  forming  a  fair  sample  of  Globigerina  ooze  from  near 
St.    Thomas,    was  carefully  washed,    and    subjected    by    Mr. 


in  EXPEDITION  OF   THE   "CHALLENGER"         99 

Buchanan  to  the  action  of  weak  acid  ;  and  he  found  that  there 
remained  after  the  carbonate  of  lime  had  been  removed,  about 
1  per  cent,  of  a  reddish  mud,  consisting  of  silica,  alumina,  and 
the  red  oxide  of  iron.  This  experiment  has  been  frequently 
repeated  with  different  samples  of  Globigerin%  ooze,  and  always 
with  the  result  that  a  small  proportion  of  a  red  sediment  re- 
mains, which  possesses  ail  the  characters  of  the  red  clay." 
♦  ♦  *  «  « 

"  It  seems  evident  from  the  observations  here  recorded,  that 
clay,  which  we  have  hitherto  looked  upon  as  essentially  the 
product  of  the  disintegration  of  older  rocks,  may  be,  under 
certain  circumstances,  an  organic  formation  like  chalk  ;  that,  as 
a  matter  of  fact,  an  area  on  the  surface  of  the  globe,  which  we 
have  shown  to  be  of  vast  extent,  although  we  are  still  far  from 
having  ascertained  its  limits,  is  being  covered  by  such  a  deposit 
at  the  present  day. 

"  It  is  impossible  to  avoid  associating  such  a  formation  with 
the  fine,  smooth,  homogeneous  clays  and  schists,  poor  in  fossils, 
but  showing  worm-tubes  and  tracks,  and  bunches  of  doubtful 
branching  things,  such  as  Oldhamia,  silicious  sponges,  and 
thin-shelled  peculiar  shrimps.  Such  formations,  more  or  less 
metamorphosed,  are  very  familiar,  especially  to  the  student  of 
palaeozoic  geology,  and  they  often  attain  a  vast  thickness.  One 
is  inclined,  from  the  great  resemblance  between  them  in  com- 
position and  in  the  general  character  of  the  included  fauna,  to 
suspect  that  these  may  be  organic  formations,  like  the  modem 
red  clay  of  the  Atlantic  and  Southern  Sea,  accumulations  of  the 
insoluble  ashes  of  shelled  creatures. 

"The  dredging  in  the  red  clay  on  the  13th  of  March  was 
unusually  rich.  The  bag  contained  examples,  those  with  cal- 
careous shells  rather  stunted,  of  most  of  the  characteristic  deep- 
water  groups  of  the  Southern  Sea,  including  Uonhcllularia, 
Eupledella,  PtcrocriniLS,  Brisinga,  Ophioglypha,  Pourtalesia, 
and  one  or  two  Mullusca.  This  is,  however,  very  rarely  the 
case.  Generally  the  red  clay  is  barren,  or  contains  only  a  very- 
small  number  of  forms. 

It  must  be  admitted  that  it  is  very  diflScult,  at 


100       EXPEDITION   OF  THE   "CHALLENGER"         m 

present,  to  frame  any  satisfactory  explanation  of 
the  mode  of  origin  of  this  singular  deposit  of  red 
clay. 

I  cannot  say  that  the  theory  put  forward 
tentatively,  and  with  much  reservation  by  Pro- 
fessor Thomson,  that  the  calcareous  matter  is 
dissolved  out  by  the  relatively  fresh  water  of  the 
deep  currents  from  the  Antarctic  regions,  appears 
satisfactory  to  me.  Nor  do  I  see  my  way  to  the 
acceptance  of  the  suggestion  of  Dr.  Carpenter,  that 
the  red  clay  is  the  result  of  the  decomposition  of 
previously-formed  greensand.  At  present  there  is 
no  evidence  that  greensand  casts  are  ever  formed 
at  great  depths;  nor  has  it  been  proved  that 
Glauconite  is  decomposable  by  the  agency  of  water 
and  carbonic  acid. 

I  think  it  probable  that  we  shall  have  to  wait 
some  time  for  a  sufficient  explanation  of  the  origin 
of  the  abyssal  red  clay,  no  less  than  for  that  of  the 
sublittoral  greensand  in  the  intermediate  zone. 
But  the  importance  of  the  establishment  of  the 
fact  that  these  various  deposits  are  being  formed 
in  the  ocean,  at  the  present  day,  remains  the  same, 
whether  its  rationale  be  understood  or  not. 

For,  suppose  the  globe  to  be  evenly  covered  with 
sea,  to  a  depth  say  of  a  thousand  fathoms — then, 
whatever  might  be  the  mineral  matter  composing 
the  sea-bottom,  little  or  no  deposit  would  be 
formed  upon  it,  the  abrading  and  denuding  action 
of  water,  at  such  a  depth,  being  exceedingly  sHght 


Ill         EXPEDITION  OF   THE   "CHALLENGER"       101 

Next,  imagine  sponges,  Radiolaria,  Foraminifera, 
and  diatcmaceous  plants,  such  as  those  which  now 
exist  in  the  deep-sea,  to  be  introduced :  they 
would  be  distributed  according  to  the  same  laws 
as  at  present,  the  sponges  (and  possibly  some  of 
the  Formninifera)  covering  the  bottom,  while  other 
Foraminifera,  with  the  Radiolaria  and  Diatomacew, 
would  increase  and  multiply  in  the  surface  waters. 
In  accordance  with  the  existing  state  of  thino-s, 
the  Radiolaria  and  Diatoms  would  have  a  universal 
distribution,  the  latter  gathering  most  thickly  in 
the  polar  regions,  while  the  Foraminifera  would 
be  largely,  if  not  exclusively,  confined  to  the  inter- 
mediate zone ;  and,  as  a  consequence  of  this  distri- 
bution, a  bed  of  "  chalk  "  would  begin  to  form  in 
the  intermediate  zone,  while  caps  of  silicious  rock 
would  accumulate  on  the  circumpolar  regions. 

Suppose,  further,  that  a  part  of  the  intermediate 
area  were  raised  to  within  two  or  three  hundred 
fathoms  of  the  surface — for  an3rthing  that  we  know 
to  the  contrary,  the  change  of  level  might  deter- 
mine the  substitution  of  greensand  for  the 
"  chalk  "  ;  while,  on  the  other  hand,  if  part  of 
the  same  area  were  depressed  to  three  thousand 
fathoms,  that  change  might  determine  the  substi- 
tution of  a  different  silicate  of  alumina  and  iron — • 
namely,  clay — for  the  "  chalk  "  that  would  other- 
wise be  formed. 

If  the  Challenger  hypothesis,  that  the  red 
clay  is  the  residue  left  by  dissolved  Foraminiferous 


102       EXPEDITION   OF  THE   "CHALLENGER"  m 

skeletons,  is  correct,  then  all  these  deposits  ahke 
would  be  directly,  or  indirectly,  the  product  of 
living  organisms.  But  just  as  a  silicious  deposit 
may  be  metamorphosed  into  opal  or  quartzite,  and 
chalk  into  marble,  so  known  metamorphic  agencies 
may  metamorphose  clay  into  schist,  clay-slate,  slate, 
gneiss,  or  even  granite.  And  thus,  by  the  agency 
of  the  lowest  and  simplest  of  organisms,  our 
imaginary  globe  might  be  covered  with  strata,  of 
all  the  chief  kinds  of  rock  of  which  the  known 
crust  of  the  earth  is  composed,  of  indefinite  thick- 
ness and  extent. 

The  bearing  of  the  conclusions  which  are  now 
either  estabhshed,  or  highly  probable,  respecting 
the  origin  of  silicious,  calcareous,  and  clayey  rocks, 
and  their  metamorphic  derivatives,  upon  the 
archaeology  of  the  earth,  the  elucidation  of  which 
is  the  ultimate  object  of  the  geologist,  is  of  no 
small  importance. 

A  hundred  years  ago  the  singular  insight  of 
Linnseus  enabled  him  to  say  that  "  fossils  are  not 
the  children  but  the  parents  of  rocks,"  ^  and  the 

1  "Petrificata  montium  calcariorum  non  filii  sed  parentes 
snnt,  cum  omnis  calx  oriatiir  ab  anima]ibus." — Sy sterna  Naiurce, 
YA.  xii.,  t.  iii.,  p.  154.  It  must  be  recollected  that  Linnjeus 
included  silex,  as  "well  as  limestone,  under  the  name  of  "  calx," 
and  that  he  would  probably  have  arranged  Diatoms  among 
animals,  as  part  of  "chaos."  Ehrenberg  quotes  another  even 
more  pithy  passage,  which  I  have  not  been  able  to  find  in  any 
edition  of  the  Systema  accessible  to  me:  **Sic  lapides  ab 
animalibus,  nee  \ice  versa.  Sic  rupes  saxei  non  primaevi,  sed 
temporis  filiaa." 


m  EXPEDITION   OF   THE   "  CHALLENGER "      103 

whole  efifect  of  the  discoveries  made  since  his  time 
has  been  to  compile  a  larger  and  larger  comment- 
ary upon  this  text.  It  is,  at  present,  a  perfectly- 
tenable  hypothesis  that  all  silicious  and  calcareous 
rocks  are  either  directly,  or  indirectly,  derived  from 
material  which  has,  at  one  time  or  other,  formed 
part  of  the  organized  framework  of  living  organ- 
isms. Whether  the  same  generalization  may  be 
extended  to  aluminous  rocks,  depends  upon  the 
conclusion  to  be  drawn  from  the  facts  respecting 
the  red  clay  areas  brought  to  light  by  the 
Challenger.  If  we  accept  the  view  taken  by 
Wyville  Thomson  and  his  colleagues — that  the 
red  clay  is  the  residuum  left  after  the  calcareous 
matter  of  the  Globigerinm  ooze  has  been  dissolved 
away — then  clay  is  as  much  a  product  of  life  as 
limestone,  and  all  known  derivatives  of  clay  may 
have  formed  part  of  animal  bodies. 

So  long  as  the  Glohigerinoe,  actually  collected  at 
the  surface,  have  not  been  demonstrated  to  con- 
tain the  elements  of  clay,  the  Challenger  hypo- 
thesis, as  I  may  term  it,  must  be  accepted  with 
reserve  and  provisionally,  but,  at  present,  I  cannot 
but  think  that  it  is  more  probable  than  any  other 
suggestion  which  has  been  made. 

Accepting  it  provisionally,  we  arrive  at  the 
remarkable  result  that  all  the  chief  known  con- 
stituents of  the  crust  of  the  earth  may  have 
formed  part  of  living  bodies ;  that  they  may  be 
the  "  ash  "  of  protoplasm ;  that  the  "  riLpes  saxei " 


104       EXPEDITION   OF   THE   "CHALLENGER"        iii 

are  not  only  "  temporis,"  but  "  vitce  filice  *' ;  and, 
consequently,  that  the  time  during  which  life  has 
been  active  on  the  globe  may  be  indefinitely 
greater  than  the  period,  the  commencement  of 
which  is  marked  by  the  oldest  known  rocks, 
whether  fossiliferous  or  unfossiliferous. 

And  thus  we  are  led  to  see  where  the  solution 
of  a  great  problem  and  apparent  paradox  of 
geology  may  lie.  Satisfactory  evidence  now  exists 
that  some  animals  in  the  existing  world  have  been 
derived  by  a  process  of  gradual  modification  from 
pre-existing  forms.  It  is  undeniable,  for  example, 
that  the  evidence  in  favour  of  the  derivation  of 
the  horse  from  the  later  tertiary  Hipparion,  and 
that  of  the  Hipparion  from  AncJiithermm,  is  as 
complete  and  cogent  as  such  evidence  can  reason- 
ably be  expected  to  be ;  and  the  further  investiga- 
tions into  the  history  of  the  tertiary  mammalia  are 
pushed,  the  greater  is  the  accumulation  of  evidence 
having  the  same  tendency.  So  far  from  palae- 
ontology lending  no  support  to  the  doctrine  of 
evolution — as  one  sees  constantly  asserted — that 
doctrine,  if  it  had  no  other  support,  would  have 
been  irresistibly  forced  upon  us  by  the  palseonto- 
logical  discoveries  of  the  last  twenty  years. 

If,  however,  the  diverse  forms  of  life  which  now 
exist  have  been  produced  by  the  modification  ©f 
previously-existing  less  divergent  forms,  the  recent 
and  extinct  species,  taken  as  a  whole,  must  fall 
into  series  which  must  converge  as  we  go  back  in 


Ill  EXPEDITION   OF   THE   "challenger"      105 

time.  Hence,  if  the  period  represented  by  the 
rocks  is  greater  than,  or  co-extensive  with,  that 
during  which  hfe  has  existed,  we  ought,  some- 
where among  the  ancient  formations,  to  an'ive  at 
the  point  to  which  all  these  series  converge,  or 
from  which,  in  other  words,  they  have  diverged — - 
the  primitive  undifferentiated  protoplasmic  living 
things,  whence  the  two  great  series  of  plants  and 
animals  have  taken  their  departure. 

But,  as  a  matter  of  fact,  the  amount  of  conver- 
gence of  series,  in  relation  to  the  time  occupied  by 
the  deposition  of  geological  formations,  is  extra- 
ordinarily small.  Of  all  animals  the  higher 
Vertehrata  are  the  most  complex ;  and  among 
these  the  carnivores  and  hoofed  animals  (  Ungulata) 
are  highly  differentiated.  Nevertheless,  although 
the  different  lines  of  modification  of  the  Carnivora 
and  those  of  the  Ungidata,  respectively,  approach 
one  another,  and,  although  each  group  is  repre- 
sented by  less  differentiated  forms  in  the  older 
tertiary  rocks  than  at  the  present  day,  the  oldest 
tertiary  rocks  do  not  bring  us  near  the  primitive 
form  of  either.  If,  in  the  same  way,  the  conver- 
gence of  the  varied  forms  of  reptiles  is  measured 
against  the  time  during  which  their  remains  are 
preserved — which  is  represented  by  the  whole  of 
the  tertiary  and  mesozoic  formations — the  amount 
of  that  convergence  is  far  smaller  than  that  of  the 
lines  of  mammals,  between  the  present  time  and 
the  beginning  of  the  tertiary  epoch.     And  it  is  a 


106       EXPEDITION   OF   THE   "CHALLENGER"         m 

broad  fact  that,  the  lower  we  go  in  the  scale  of 

organization,  the  fewer  signs  are  there  of  con- 
vergence towards  the  primitive  form  from  whence 
all  must  have  diverged,  if  evolution  be  a  fact. 
Nevertheless,  that  it  is  a  fact  in  some  cases,  is 
proved,  and  I,  for  one,  have  not  the  courage  to 
suppose  that  the  mode  in  which  some  species  have 
taken  their  origin  is  different  from  that  in  which 
the  rest  have  originated. 

What,  then,  has  become  of  all  the  marine 
animals  which,  on  the  h}^othesis  of  evolution, 
must  have  existed  in  myriads  in  those  seas,  wherein 
the  many  thousand  feet  of  Cambrian  and  Lauren- 
tian  rocks  now  devoid,  or  almost  devoid,  of  any 
trace  of  life  were  deposited  ? 

Sir  Charles  Lyell  long  ago  suggested  that  the 
azoic  character  of  these  ancient  formations  might 
be  due  to  the  fact  that  they  had  undergone 
extensive  metamorphosis ;  and  readers  of  the 
"  Principles  of  Geology  "  will  be  familiar  with  the 
ingenious  manner  in  which  he  contrasts  the  theory 
of  the  Gnome,  who  is  acquainted  only  with  the 
interior  of  the  earth,  with  those  of  ordinaiy 
philosophers,  who  know  only  its  exterior. 

The  metamorphism  contemplated  by  the  great 
modern  champion  of  rational  geology  is,  mainly, 
that  brought  about  by  the  exposure  of  rocks  to 
subterranean  heat ;  and  where  no  such  heat  could 
be  sho^vn  to  have  operated,  his  opponents  as- 
sumed that  no  metamorphosis  could  have  taken 


Ill  EXPEDITION  OF   THE   "CHALLENGER**      107 

place.  But  the  formation  of  greensand,  and  still 
more  that  of  the  "red  clay"  (if  the  Challenger 
hypothesis  be  correct)  affords  an  insight  into  a 
new  kind  of  metamorphosis — not  igneous,  but 
aqueous — by  which  the  primitive  nature  of  a 
deposit  may  be  masked  as  completely  as  it  can  be 
by  the  agency  of  heat.  And,  as  Wyville  Thomson 
suggests,  in  the  passage  I  have  quoted  above  (p. 
17),  it  further  enables  us  to  assign  a  new  cause 
for  the  occurrence,  so  puzzling  hitherto,  of 
thousands  of  feet  of  unfossiliferous  fine-grained 
schists  and  slates,  in  the  midst  of  formations 
deposited  in  seas  which  certainly  abounded  in  life. 
If  the  great  deposit  of  "  red  clay  "  now  forming  in 
the  eastern  valley  of  the  Atlantic  were  meta- 
morphosed into  slate  and  then  upheaved,  it  would 
constitute  an  "  azoic "  rock  of  enormous  extent. 
And  yet  that  rock  is  now  forming  in  the  midst  of 
a  sea  which  swarms  with  living  beings,  the  great 
majority  of  which  are  provided  with  calcareous  or 
silicious  shells  and  skeletons ;  and,  therefore,  are 
such  as,  up  to  this  time,  we  should  have  termed 
eminently  preservable. 

Thus  the  discoveries  made  by  the  Challenger 
expedition,  like  all  recent  advances  in  our 
knowledge  of  the  phenomena  of  biology,  or 
of  the  changes  now  being  effected  in  the 
structure  of  the  surface  of  the  earth,  are  in 
accordance  with,  and  lend  strong  support  to, 
that  doctrine   of  Uniformitarianism,  which,  fifty 


108       EXPEDITION  OF  THE   "CHALLENGER"         m 

years  ago,  was  held  only  by  a  small  minority  of 
English  geologists — Lyell,  Scrope,  and  De  la  Beche 
• — but  now,  thanks  to  the  long-continued  labours 
of  the  first  two,  and  mainly  to  those  of  Sir  Charles 
Lyell,  has  gradually  passed  from  the  position  of  a 
heresy  to  that  of  catholic  doctrine. 

Applied  within  the  limits  of  the  time  registered 
by  the  known  fraction  of  the  crust  of  the  earth, 
I  believe  that  uniformitarianism  is  unassailable. 
The  evidence  that,  in  the  enormous  lapse  of  time 
between  the  deposition  of  the  lowest  Laurentian 
strata  and  the  present  day,  the  forces  which  have 
modified  the  surface  of  the  crust  of  the  earth  were 
different  in  kind,  or  greater  in  the  intensity  of 
their  action,  than  those  which  are  now  occupied  in 
the  same  work,  has  yet  to  be  produced.  Such 
evidence  as  we  possess  all  tends  in  the  contrary 
direction,  and  is  in  favour  of  the  same  slow  and 
gradual  changes  occurring  then  as  now. 

But  this  conclusion  in  nowise  conflicts  with  the 
deductions  of  the  physicist  from  his  no  less  clear 
and  certain  data.  It  may  be  certain  that  this 
globe  has  cooled  down  from  a  condition  in  which 
life  could  not  have  existed  ;  it  may  be  certain  that, 
in  so  cooling,  its  contracting  crust  must  have 
undergone  sudden  convulsions,  which  were  to  our 
earthquakes  as  an  earthquake  is  to  the  vibration 
caused  by  the  periodical  eruption  of  a  Geyser ;  but 
in  that  case,  the  earth  must,  like  other  respectable 
parents,  have  sowed  her  wild  oats,  and  got  through 


Ill  EXPEDITION   OF   THE   "CHALLENGER"      109 

her  turbulent  youth,  before  we,  her  children,  have 
any  knowledge  of  her. 

So  far  as  the  evidence  afforded  by  the  super- 
ficial crust  of  the  earth  goes,  the  modern  geologist 
can,  ex  animo,  repeat  the  saying  of  Hutton,  "  We 
find  no  vestige  of  a  beginning — no  prospect  of  an 
end."  However,  he  will  add,  with  Hutton,  "  But 
in  thus  tracing  back  the  natural  operations  which 
have  succeeded  each  otter,  and  mark  to  us  the 
course  of  time  past,  we  come  to  a  period  in  which 
we  cannot  see  any  further."  And  if  he  seek  to 
peer  into  the  darkness  of  this  period,  he  will 
welcome  the  light  proffered  by  physics  and 
mathematics. 


IV 

YEAST 

[1871] 

It  has  been  known,  from  time  immemorial,  that 
the  sweet  liquids  which  may  be  obtained  by  ex- 
pressing the  juices  of  the  fruits  and  stems  of 
various  plants,  or  by  steeping  malted  barley  in  hot 
water,  or  by  mixing  honey  with  water — are  liable 
to  undergo  a  series  of  very  singular  changes,  if 
freely  exposed  to  the  air  and  left  to  themselves,  in 
warm  weather.  However  clear  and  pellucid  the 
liquid  may  have  been  when  first  prepared,  however 
carefully  it  may  have  been  freed,  by  straining  and 
filtration,  from  even  the  finest  visible  impurities, 
it  will  not  remain  clear.  After  a  time  it  will 
become  cloudy  and  turbid ;  little  bubbles  will  be 
seen  rising  to  the  surface,  and  their  abundance  will 
increase  until  the  liquid  hisses  as  if  it  were  sim- 
mering on  the  fire.  By  degrees,  some  of  the  solid 
particles  which  produce  the  turbidity  of  the  liquid 


IV  YEAST  111 

collect  at  its  surface  into  a  scum,  which  is  blown 
up  by  the  emerging  air-bubbles  into  a  thick,  foamy 
froth.  Another  moiety  sinks  to  the  bottom,  and 
accumulates  as  a  muddy  sediment,  or  "  lees." 

When  this  action  has  continued,  with  more  or 
less  violence,  for  a  certain  time,  it  gradually 
moderates.  The  evolution  of  bubbles  slackens, 
and  finally  comes  to  an  end ;  scum  and  lees  alike 
settle  at  the  bottom,  and  the  fluid  is  once  more 
clear  and  transparent.  But  it  has  acquired 
properties  of  which  no  trace  existed  in  the 
original  liquid.  Instead  of  being  a  mere  sweet 
fluid,  mainly  composed  of  sugar  and  water,  the 
sugar  has  more  or  less  completely  disappeared ;  and 
it  has  acquired  that  peculiar  smell  and  taste  which 
we  call  "  spirituous."  Instead  of  being  devoid  of 
any  obvious  effect  upon  the  animal  economy,  it 
has  become  possessed  of  a  very  wonderful  influence 
on  the  nervous  system ;  so  that  in  small  doses  it 
exhilarates,  while  in  larger  it  stupefies,  and  may 
even  destroy  life. 

Moreover,  if  the  original  fluid  is  put  into  a  still, 
and  heated  moderately,  the  first  and  last  product 
of  its  distillation  is  simple  water ;  while,  when  the 
altered  fluid  is  subjected  to  the  same  process,  the 
matter  which  is  first  condensed  in  the  receiver  is 
found  to  be  a  clear,  volatile  substance,  which  is 
hghter  than  water,  has  a  pungent  taste  and  smell, 
possesses  the  intoxicating  powers  of  the  fluid  in 
an  eminent  degree,  and  takes  fire  the  moment  it 


112  YEAST 


IV 


is  brought  in  contact  with  a  flame.  The  Al- 
chemists called  this  volatile  liquid,  which  they 
obtained  from  wine,  "  spirits  of  wine,"  just  as  they 
called  hydrochloric  acid  "  spirits  of  salt,"  and  as 
we,  to  this  day,  call  refined  turpentine  "  spirits  of 
turpentine."  As  the  "  spiritus,"  or  breath,  of  a 
man  was  thought  to  be  the  most  refined  and 
subtle  part  of  him,  the  intelligent  essence  of  man 
was  also  conceived  as  a  sort  of  breath,  or  spirit ; 
and,  by  analogy,  the  most  refined  essence  of  any- 
thing was  called  its  "  spirit."  And  thus  it  has 
come  about  that  we  use  the  same  word  for  the 
soul  of  man  and  for  a  glass  of  gin. 

At  the  present  day,  however,  we  even  more 
commonly  use  another  name  for  this  peculiar 
liquid — namely,  "  alcohol,"  and  its  origin  is  not 
less  singular.  The  Dutch  physician,  Van  Helmont, 
lived  in  the  latter  part  of  the  sixteenth  and  the 
beginning  of  the  seventeenth  century — in  the 
transition  period  between  alchemy  and  chemistry 
— and  was  rather  more  alchemist  than  chemist. 
Appended  to  his  "  Opera  Omnia,"  published  in  1707, 
there  is  a  very  needful  "  Clavis  ad  obscuriorum 
sensum  referendum,"  in  which  the  following 
passage  occurs : — 

"Alcohol. — Chymicis  est  liquor  ant  pulvis  siimme  subtili- 
satns,  vocabulo  Oiientalibus  quoque,  cum  primis  Habessinis, 
familiari,  quibus  cohol  speciatim  pulverem  impalpabilem  ex 
antimonio  pro  oculis  tingendis  denotat  .  .  .  Hodie  autem,  ob 
analogiam,  quivis  pulvis  tenerior,  ut  pulvis  oculorum  cancri 


IV 


YEAST  113 


summ^  subtilisatus  alcohol  audit,  haud  aliter  ac  spiritus  rectifi- 
catissimi  alcolisati  dicuntur." 

Similarly,  Robert  Boyle  speaks  of  a  fine  powder 
as  "  alcohol " ;  and,  so  late  as  the  middle  of  the 
last  century,  the  English  lexicographer,  Nathan 
Bailey,  defines  "  alcohol "  as  "  the  pure  substance 
of  anything  separated  from  the  more  gross,  a  very 
fine  and  impalpable  powder,  or  a  very  pure,  well- 
rectified  spirit."  But,  by  the  time  of  the  publi- 
cation of  Lavoisier's  "  Traite  Elementaire  de 
Chimie,"in  1789,  the  term  "alcohol,"  "  alkohol," 
or  "  alkool "  (for  it  is  spelt  in  all  three  ways),  which 
Van  Helmont  had  applied  primarily  to  a  fine 
powder,  and  only  secondarily  to  spirits  of  wine,  had 
lost  its  primary  meaning  altogether;  and,  from 
the  end  of  the  last  century  until  now,  it  has,  I 
believe,  been  used  exclusively  as  the  denotation  of 
spirits  of  wine,  and  bodies  chemically  allied  to  that 
substance. 

The  process  which  gives  rise  to  alcohol  in  a 
saccharine  fluid  is  known  to  us  as  "  fermentation  " ; 
a  term  based  upon  the  apparent  boiling  up  or 
''  effervescence "  of  the  fermenting  liquid,  and  of 
Latin  origin. 

Our  Teutonic  cousins  call  the  same  process 
"giihren,"  "gasen,"  "goschen,"  and  "gischen"; 
but,  oddly  enough,  we  do  not  seem  to  have 
retained  their  verb  or  their  substantive  denot- 
ing the  action  itself,  though  we  do  use  names 
identical  with,  or  plainly  derived  fi:om,  theirs  for 

194 


114  YEAST  IV 

the  scum  and  lees.  These  are  called,  in  Low 
German,  "  giischt "  and  "  gischt " ;  in  Anglo-Saxon, 
"gest,"  "gist,"  and  "yst,"  whence  our  "yeast." 
Again,  in  Low  German  and  in  Anglo-Saxon  there 
is  another  name  for  yeast,  having  the  form  "  barm," 
or  "  beorm " ;  and,  in  the  Midland  Counties, 
"  barm  "  is  the  name  by  which  yeast  is  still  best 
known.  In  High  German,  there  is  a  third  name 
for  yeast,  "  hefe,"  which  is  not  represented  in 
English,  so  far  as  I  know. 

All  these  words  are  said  by  philologers  to  be 
derived  from  roots  expressive  of  the  intestine 
motion  of  a  fermenting  substance.  Thus  "  hefe  " 
is  derived  from  "  heben,"  to  raise ;  "  barm "  from 
"  beren  "  or  "  baren,"  to  bear  up ;  "  yeast,"  "  yst," 
and  "  gist,"  have  all  to  do  with  seething  and  foam, 
with  "  yeasty  "  waves,  and  "  gusty  "  breezes. 

The  same  reference  to  the  swelling  up  of  the 
fermenting  substance  is  seen  in  the  Gallo-Latin 
terms  "  levure  "  and  "  leaven." 

It  is  highly  creditable  to  the  ingenuity  of  our 
ancestors  that  the  peculiar  property  of  fermented 
liquids,  in  virtue  of  which  they  "  make  glad  the 
heart  of  man,"  seems  to  have  been  known  in  the 
remotest  periods  of  which  we  have  any  record. 
All  savages  take  to  alcoholic  fluids  as  if  they 
were  to  the  manner  bom.  Our  Vedic  forefathers 
intoxicated  themselves  with  the  juice  of  the 
"  soma " ;  Noah,  by  a  not  unnatural  reaction 
against  a  superfluity  of  water,  appears   to   have 


IV 


YEAST  115 


taken  the  earliest  practicable  opportunity  cf 
qualifying  that  which  he  was  obliged  to  drink; 
and  the  ghosts  of  the  ancient  Egyptians  were 
solaced  by  pictures  of  banquets  in  which  the 
wine-cup  passes  round,  graven  on  the  walls  of 
their  tombs.  A  knowledge  of  the  process  of 
fermentation,  therefore,  was  in  all  probability 
possessed  by  the  prehistoric  populations  of  the 
globe ;  and  it  must  have  become  a  matter  of  great 
interest  even  to  primgeval  wine-bibbers  to  study 
the  methods  by  which  fermented  liquids  could 
be  surely  manufactured.  No  doubt  it  was  soon 
discovered  that  the  most  certain,  as  well  as 
the  most  expeditious,  way  of  making  a  sweet  juice 
ferment  was  to  add  to  it  a  little  of  the  scum,  or 
lees,  of  another  fermenting  juice.  And  it  can 
hardly  be  questioned  that  this  singular  excitation 
of  fermentation  in  one  fluid,  by  a  sort  of  infection, 
or  inoculation,  of  a  little  ferment  taken  from  some 
other  fluid,  together  with  the  strange  swelling, 
foaming,  and  hissing  of  the  fermented  substance, 
must  have  always  attracted  attention  from  the 
more  thoughtful.  Nevertheless,  the  commence- 
ment of  the  scientific  analysis  of  the  phenomena 
dates  from  a  period  not  earlier  than  the  first  half 
of  the  seventeenth  century. 

At  this  time,  Van  Helmont  made  a  first  step, 
by  pointing  out  that  the  peculiar  hissing  and 
bubbling  of  a  fermented  liquid  is  due,  not  to  the 
evolution  of  common  air  (which  he,  as  the  inventoi 


116  YEAST  IV 

of  the  term  "  gas,"  calls  "  gas  ventosum  "),  but  to 
that  of  a  peculiar  kind  of  air  such  as  is  occasionally 
met  with  in  caves,  mines,  and  wells,  and  which 
he  calls  "  gas  sylvestre." 

But  a  century  elapsed  before  the  nature  of  this 
"gas  sylvestre,"  or,  as  it  was  afterwards  called, 
"fixed  air,"  was  clearly  determined,  and  it  was 
found  to  be  identical  with  that  deadly  "  choke- 
damp  "  by  which  the  lives  of  those  who  descend 
into  old  wells,  or  mines,  or  brewers'  vats,  are 
sometimes  suddenly  ended  ;  and  with  the  poisonous 
aeriform  fluid  which  is  produced  by  the  combus- 
tion of  charcoal,  and  now  goes  by  the  name  of 
carbonic  acid  gas. 

During  the  same  time  it  gradually  became 
evident  that  the  presence  of  sugar  was  essential  to 
the  production  of  alcohol  and  the  evolution  of 
carbonic  acid  gas,  which  are  the  two  great  and 
conspicuous  products  of  fermentation.  And  finally, 
in  1787,  the  ItaHan  chemist,  Fabroni,  made  the 
capital  discovery  that  the  yeast  ferment,  the 
presence  of  which  is  necessary  to  fermentation, 
is  what  he  termed  a  "  vegeto-animal "  substance  ; 
that  is,  a  body  which  gives  off  ammoniacal  salts 
when  it  is  burned,  and  is,  in  other  ways,  similar 
to  the  gluten  of  plants  and  the  albumen  and 
casein  of  animals. 

These  discoveries  prepared  the  way  for  the 
illustrious  Frenchman,  Lavoisier,  who  first  ap- 
proached  the   problem   of  fermentation   with    a 


IV 


YEAST  11' 


complete  conception  of  the  nature  of  the  work  to 
be  done.  The  words  in  which  he  expresses  this 
conception,  in  the  treatise  on  elementary  chemistry 
to  which  reference  has  already  been  made,  mark 
the  year  1789  as  the  commencement  of  a  revolu- 
tion of  not  less  moment  in  the  world  of  science 
than  that  which  simultaneously  burst  over  the 
political  world,  and  soon  engulfed  Lavoisier  himself 
in  one  of  its  mad  eddies. 


"We  may  lay  it  down  as  an  incontestable  axiom  that,  in  all 
the  operations  of  art  and  nature,  nothing  is  created  ;  an  equal 
quantity  of  matter  exists  both  before  and  after  the  experiment : 
the  quality  and  quantity  of  the  elements  remain  precisely  the 
same,  and  nothing  takes  place  beyond  changes  and  modifications 
in  the  combinations  of  these  elements.  Upon  this  principle  the 
whole  art  of  performing  chemical  experiments  depends  ;  we 
must  always  suppose  an  exact  equality  between  the  elements  of 
the  body  examined  and  those  of  the  products  of  its  analysis. 

"Hence,  since  from  must  of  grapes  we  procure  alcohol  arid 
carbonic  acid,  I  have  an  undoubted  right  to  suppose  that  must 
consists  of  carbonic  acid  and  alcohol.  From  these  premisses  we 
have  two  modes  of  ascertaining  what  passes  during  vinous  fer- 
mentation :  either  by  determining  the  nature  of,  and  the  elements 
which  compose,  the  fermentable  substances  ;  or  by  accurately  ex- 
amining the  products  resulting  from  fermentation  ;  and  it  is  evi- 
dent that  the  knowledge  of  either  of  these  must  lead  to  accurate 
conclusions  concerning  the  nature  and  composition  of  the  other. 
From  these  considerations  it  became  necessary  accurately  to 
determine  the  constituent  elements  of  the  fermentable  sub- 
stances ;  and  for  this  purpose  I  did  not  make  use  of  the  com- 
pound juices  of  fruits,  the  rigorous  analysis  of  which  is  perhaps 
impossible,  but  made  choice  of  sugar,  which  is  easily  analysed, 
and  the  nature  of  which  I  have  already  explained.  This  sub- 
Btance  is  a  true  vegetable  oxyd,  with  two  bases,  composed  of 


118  YEAST  IV 

li3'drogen  and  carbon,  brought  to  the  state  of  an  oxyd  by  means 
of  a  certain  proportion  of  oxygen  ;  and  these  three  elements  are 
combined  in  such  a  way  that  a  very  slight  force  is  sufficient  to 
destroy  the  equilibrium  of  their  connection." 

After  giving  the  details  of  his  analysis  of  sugar 
and  of  the  products  of  fermentation,  Lavoisier 
continues : — 

"The  effect  of  the  vinous  fermentation  upon  sugar  is  thus 
reduced  to  the  mere  separation  of  its  elements  into  two  portions  ; 
one  part  is  oxygenated  at  the  expense  of  the  other,  so  as  to  form 
carbonic  acid  ;  while  the  other  part,  being  disoxygenated  in 
favour  of  the  latter,  is  converted  into  the  combustible  substance 
called  alkohol  ;  therefore,  if  it  were  possible  to  re-unite  alkohol 
and  carbonic  acid  together,  we  ought  to  form  sugar."  ^ 

Thus  Lavoisier  thought  he  had  demonstrated 
that  the  carbonic  acid  and  the  alcohol  which  are 
produced  by  the  process  of  fermentation,  are 
equal  in  weight  to  the  sugar  which  disappears; 
but  the  application  of  the  more  refined  methods 
of  modem  chemistry  to  the  investigation  of  the 
products  of  fermentation  by  Pasteur,  in  1860, 
proved  that  this  is  not  exactly  true,  and  that 
there  is  a  deficit  of  from  5  to  7  per  cent,  of  the 
sugar  which  is  not  covered  by  the  alcohol  and 
carbonic  acid  evolved.  The  greater  part  of  this 
deficit  is  accounted  for  by  the  discovery  of  two 
substances,  glycerine  and  succinic  acid,  of  the 
existence  of  which  Lavoisier  was  unaware,  in  the 


^  Elements  of  ChemUtry.     By  M.  Lavoisier.     Translated  by 
Robert  Kerr.     Second  Edition,  1793  (pp.  186—196). 


rv 


YEAST  119 


fermented  liquid.  But  about  IJ  per  cent,  still 
remains  to  be  made  good.  According  to  Pasteur, 
it  has  been  appropriated  by  the  yeast,  but  the 
fact  that  such  appropriation  takes  place  cannot 
be  said  to  be  actually  proved. 

However  this  may  be,  there  can  be  no  doubt 
that  the  constituent  elements  of  fully  98  per 
cent,  of  the  sugar  which  has  vanished  during 
fermentation  have  simply  undergone  rearrange- 
ment ;  like  the  soldiers  of  a  brigade,  w^ho  at  the 
word  of  command  divide  themselves  into  the 
independent  regiments  to  which  they  belong. 
The  brigade  is  sugar,  the  regiments  are  carbonic 
acid,  succinic  acid,  alcohol,  and  glycerine. 

From  the  time  of  Fabroni,  onwards,  it  has  been 
admitted  that  the  agent  by  which  this  surprising 
rearrangement  of  the  particles  of  the  sugar  is 
effected  is  the  yeast.  But  the  first  thoroughly 
conclusive  evidence  of  the  necessity  of  yeast  for 
the  fermentation  of  sugar  was  furnished  by 
Appert,  whose  method  of  preserving  perishable 
articles  of  food  excited  so  much  attention  in 
France  at  the  beginning  of  this  century.  Gay- 
Lussac,  in  his  "  Memoire  sur  la  Fermentation,"  ^ 
alludes  to  Appert's  method  of  preserving  beer- 
wort  unfermented  for  an  indefinite  time,  by 
sim23ly  boiling  the  wort  and  closing  the  vessel 
in  which  the  boiling  fluid  is  contained,  in  such 
a  way  as  thoroughly  to  exclude  air;  and  he 
^  Annates  de  Chimie,  1810. 


120  YEAST  IV 

shows  that,  if  a  little  yeast  be  introduced  into 
such  wort,  after  it  has  cooled,  the  wort  at  once 
begins  to  ferment,  even  though  every  precaution 
be  taken  to  exclude  air.  And  this  statement  has 
since  received  full  confirmation  from  Pasteur. 

On  the  other  hand,  Schwann,  Schroeder  and 
Dusch,  and  Pasteur,  have  amply  proved  that  air 
may  be  allowed  to  have  free  access  to  beer-wort, 
without  exciting  fermentation,  if  only  efficient 
precautions  are  taken  to  prevent  the  entry  of 
particles  of  yeast  along  with  the  air. 

Thus,  the  truth  that  the  fermentation  of  a 
simple  solution  of  sugar  in  water  depends  upon 
the  presence  of  yeast,  rests  upon  an  unassailable 
foundation;  and  the  inquiry  into  the  exact 
nature  of  the  substance  which  possesses  such  a 
wonderful  chemical  influence  becomes  profoundly 
interesting. 

The  first  step  towards  the  solution  of  this 
problem  was  made  two  centuries  ago  by  the  patient 
and  painstaking  Dutch  naturalist,  Leeuwenhoek, 
who  in  the  year  1680  wrote  thus  : — 

"Ssepissime  examinavi  fermentum  cerevisise.  semperqne  hoc 
ex  globulis  per  materiam  pellncidam  fluitantibiis,  qnam  cere- 
visiam  esse  censiii,  constare  observavi :  vidi  etiara  evider_tissime, 
unumqueinque  hujus  fermenti  globiilnra  denuo  ex  sex  distinctis 
globulis  constare,  accurate  eidem  quantitate  et  fornise,  cui 
globulis  sanguinis  nostri,  respondentibns. 

*' Verum  talis  mihi  de  horam  origine  et  formatione  conceptus 
formabara  ;  globulis  nempe  ex  qnibus  farina  Tritici,  Hordei, 
Avenee,  Fagotritici,  se  constat  aquae  calore  dissolvi  et  aquse  com. 


rv 


YEAST  121 


misceii  ;  hac,  vero  aqua,  quam  cere  vis  iam  vocare  licet,  refriges- 
cente,  multos  ex  minimis  particulis  in  cerevisiacoadunaii,  et  hoc 
pacto  efficere  particulam  sive  globuliim,  qiise  sexta  pars  est 
globuli  faecis,  et  iterum  sex  ex  hisce  globulis  conjungi."  ^ 

Thus  Leeuwenhoek  discovered  that  yeast  con- 
sists of  globules  floating  in  a  fluid  ;  but  he  thought 
that  they  were  merely  the  starchy  particles  of  the 
grain  from  which  the  wort  was  made,  rearranged. 
He  discovered  the  fact  that  yeast  had  a  definite 
structure,  but  not  the  meaning  of  the  fact.  A 
century  and  a  half  elapsed,  and  the  investigation 
of  yeast  was  recommenced  almost  simultaneousl}? 
by  Cagniard  de  la  Tour  in  France,  and  by  Schwann 
and  Ktitzing  in  Germany.  The  French  observer 
was  the  first  to  publish  his  results ;  and  the  sub- 
ject received  at  his  hands  and  at  those  of  his 
colleague,  the  botanist  Turpin,  full  and  satisfactory 
investigation. 

The  main  conclusions  at  which  they  arrived  are 
these.  The  globular,  or  oval,  corpuscles  which 
float  so  thickly  in  the  yeast  as  to  make  it  muddy, 
though  the  largest  are  not  more  than  one  two- 
thousandth  of  an  inch  in  diameter,  and  the 
smallest  may  measure  less  than  one  seven- 
thousandth  of  an  inch,  are  living  organisms.  They 
multiply  with  great  rapidity  by  giving  off  minute 
buds,  which  soon  attain  the  size  of  their  parent, 
and  then  either  become  detached  or  remain 
united,  forming  the  compound  globules  of  which 
^  Leeuwenhoek,  Arcana  Naturce  Detecta.     Ed.  Nov.,  1721. 


122  YEAST  IV 

Leeuwenhoek  speaks,  thougli  the  constancy  of 
their  arrangement  in  sixes  existed  only  in  the 
worthy  Dutchman's  imagination. 

It  was  very  soon  made  out  that  these  yeast 
organisms,  to  which  Turpin  gave  the  name  of 
Torula  cerevisicv,  were  more  nearly  allied  to  the 
lower  Fungi  than  to  an}i:hing  else.  Indeed 
Turpin,  and  subsequently  Berkeley  and  Hoffmann, 
believed  that  they  had  traced  the  development  of 
the  Torula  into  the  well-known  and  very  common 
mould — the  Penicillium  glaucuin.  Other  observers 
have  not  succeeded  in  verifying  these  statements ; 
and  my  own  observations  lead  me  to  believe,  that 
while  the  connection  between  Torula  and  the 
moulds  is  a  very  close  one,  it  is  of  a  different 
nature  from  that  which  has  been  supposed.  I 
have  never  been  able  to  trace  the  development  of 
Torula  into  a  true  mould  ;  but  it  is  quite  easy  to 
prove  that  species  of  true  mould,  such  as  Peni- 
cillium, when  sown  in  an  appropriate  nidus,  such 
as  a  solution  of  tartrate  of  ammonia  and  yeast- 
ash,  in  water,  with  or  without  sugar,  give  rise  to 
Torulce,  similar  in  all  respects  to  T.  cerevisicc, 
except  that  they  are,  on  the  average,  smaller. 
Moreover,  Bail  has  observed  the  development  of  a 
Torula  larger  than  T.  ccrevisice,  from  a  Mucor,  a 
mould  allied  to  Penicillium. 

It  follows,  therefore,  that  the  Torulce,  or 
organisms  of  yeast,  are  veritable  plants  ;  and  con- 
clusive experiments  have  proved  that  the  powei 


IV  YEAST  123 

which  causes  the  rearrangement  of  the  molecules 
of  the  sugar  is  intimately  connected  with  the  life 
and  growth  of  the  plant.  In  fact,  w^hatever  arrests 
the  vital  activity  of  the  plant  also  prevents  it 
from  exciting  fermentation. 

Such  being  the  facts  with  regard  to  the  nature 
of  yeast,  and  the  changes  which  it  effects  in 
sugar,  how  are  they  to  be  accounted  for  ?  Before 
modern  chemistry  had  come  into  existence,  Stahl, 
stumbling,  with  the  stride  of  genius,  upon  the  con- 
ception which  lies  at  the  bottom  of  all  modern  views 
of  the  process,  put  forward  the  notion  that  the 
ferment,  being  in  a  state  of  internal  motion,  com- 
municated that  motion  to  the  sugar,  and  thus 
caused  its  resolution  into  new  substances.  And 
Lavoisier,  as  we  have  seen,  adopts  substantially 
the  same  view.  But  Fabroni,  full  of  the  then 
novel  conception  of  acids  and  bases  and  double 
decompositions,  propounded  the  hypothesis  that 
sugar  is  an  oxide  with  two  bases,  and  the  ferment 
a  carbonate  with  two  bases ;  that  the  carbon  of 
the  ferment  unites  with  the  oxygen  of  the  sugar, 
and  gives  rise  to  carbonic  acid ;  while  the  sugar, 
uniting  with  the  nitrogen  of  the  ferment,  pro- 
duces a  new  substance  analogous  to  opium.  This 
is  decomposed  by  distillation,  and  gives  rise  to 
alcohol.  Next,  in  1803,  Thenard  propounded  a 
hypothesis  which  partakes  somewhat  of  the  nature 
of  both  Stahl's  and  Fabroni's  views.  "  I  do  not 
believe  with    Lavoisier,"   he  says,   "  that  all  the 


1 24  YEAST 


IV 


carbonic  acid  formed  proceeds  from  tlie  sugar. 
How,  in  that  case,  could  we  conceive  the  action  of 
the  ferment  on  it  ?  I  think  that  the  first  por- 
tions of  the  acid  are  due  to  a  combination  of  the 
carbon  of  the  ferment  with  the  oxygen  of  the 
sugar,  and  that  it  is  by  carrying  ofif  a  portion  of 
oxygen  from  the  last  that  the  ferment  causes  the 
fermentation  to  commence — the  equilibrium  be- 
tween the  principles  of  the  sugar  being  disturbed, 
they  combine  afresh  to  form  carbonic  acid  and 
alcohol." 

The  three  views  here  before  us  may  be  familiarly 
exemplified  by  supposing  the  sugar  to  be  a  card- 
house.  According  to  Stahl,  the  ferment  is  some- 
body who  knocks  the  table,  and  shakes  the  card- 
house  down;  according  to  Fabroni,  the  ferment 
takes  out  some  cards,  but  puts  others  in  their 
places ;  according  to  Thenard,  the  ferment  simply 
takes  a  card  out  of  the  bottom  story,  the  result 
of  which  is  that  all  the  others  fall. 

As  chemistry  advanced,  facts  came  to  light 
which  put  a  new  face  upon  Stahl's  h}^othesis,  and 
gave  it  a  safer  foundation  than  it  previously  pos- 
sessed. The  general  nature  of  these  phenomena 
may  be  thus  stated  : — A  body.  A,  without  giving 
to,  or  taking  from,  another  body  B,  any  material 
particles,  causes  B  to  decompose  into  other  sub- 
stances, G,  D,  E,  the  sum  of  the  weights  of  which 
is  equal  to  the  weight  of  B,  which  decomposes. 

Thus,  bitter  almonds   contain  two  substances, 


IV  YEAST  125 

amygdalin  and  synaptase,  which  can  be  extracted, 
in  a  separate  state,  from  the  bitter  almonds.  The 
amygdaUn  thus  obtained,  if  dissolved  in  water, 
undergoes  no  change ;  but  if  a  little  synaptase  be 
added  to  the  solution,  the  amygdalin  sphts  up 
into  bitter  almond  oil,  prussic  acid,  and  a  kind  of 
sugar. 

A  short  time  after  Cagniard  de  la  Tour  dis- 
covered the  yeast  plant,  Liebig,  struck  with  the 
similarity  between  this  and  other  such  processes 
and  the  fermentation  of  sugar,  put  forward  the 
hypothesis  that  yeast  contains  a  substance  which 
acts  upon  sugar,  as  synaptase  acts  upon  amygdalin. 
And  as  the  synaptase  is  certainly  neither  organized 
nor  alive,  but  a  mere  chemical  substance,  Liebig 
treated  Cagniard  de  la  Tour's  discovery  with  no 
small  contempt,  and,  from  that  time  to  the  pre- 
sent, has  steadily  repudiated  the  notion  that  the 
decomposition  of  the  sugar  is,  in  any  sense,  the 
result  of  the  vital  activity  of  tiie  Tcnda.  But, 
though  the  notion  that  the  Torula  is  a  creature 
which  eats  sugar  and  excretes  carbonic  acid  and 
alcohol,  which  is  not  unjustly  ridiculed  in  the 
most  surprising  paper  that  ever  made  its  appear- 
ance in  a  grave  scientific  journal,^   may  be  un- 

^  "  Das  entrathselte  Geheimniss  der  geistigen  Gahrung  (Vor- 
laufige  briefliche  Mittheilung)"  is  the  title  of  an  anonymous 
contiibiition  to  Wohler  and  Liebig's  Jnnahn  der  Pharmacia 
for  1839,  in  which  a  somewhat  Rabelaisian  imaginary  descrip- 
tion of  the  organisation  of  the  "yeast  animals"  and  of  the 
manner  in  which  their  functions  are  performed,  is  given  with  a 


126  YEAST  IV 

tenable,  the  fact  that  the  Toridm  are  alive,  and 
that  yeast  does  not  excite  fermentation  unless  it 
contains  living  Toridoe.,  stands  fast.  Moreover,  of 
late  years,  the  essential  participation  of  living 
organisms  in  fermentation  other  than  the  alcoholic, 
has  been  clearly  made  out  by  Pasteur  and  other 
chemists. 

However,  it  may  be  asked,  is  there  any  necessary 
opposition  between  the  so-called  "  vital  "  and  the 
strictly  physico-chemical  views  of  fermentation  ? 
It  is  quite  possible  that  the  living  Torula  may 
excite  fermentation  in  sugar,  because  it  constantly 
produces,  as  an  essential  part  of  its  vital  manifes- 
tations, some  substance  which  acts  upon  the  sugar, 
just  as  the  synaptase  acts  upon  the  amygdalin. 
Or  it  may  be,  that,  without  the  formation  of  any 
such  special  substance,  the  physical  condition  of 
the  living  tissue  of  the  yeast  plant  is  sufficient  to 
effect  that  small  disturbance  of  the  equilibrium  of 
the  particles  of  the  sugar,  which  Lavoisier  thought 
sufficient  to  effect  its  decomposition. 

Platinum  in  a  very  fine  state  of  division — 
known  as  platinum  black,  or  noir  de  platine — has 

circumstantiality  worthy  of  the  author  of  GulUv'rs  Travels. 
As  a  specimen  of  the  writer's  humour,  his  account  of  what 
happens  when  fermentation  comes  to  an  end  may  suftice. 
"Sobald  namlich  die  Thiere  keinen  Zucker  mehr  vorfinden,  so 
fressen  sie  sich  gegenseitio:  selbst  auf,  was  durch  eine  eigene 
Manipulation  geschieht ;  alles  wird  verdant  his  auf  die  Eier, 
weiche  unverandert  durch  den  Darmkanal  hineingehen  ;  man 
hat  zuletzt  wieder  gahrungsfahige  Het'e,  namlich  den  Saamen 
der  Thieie,  der  iibrig  bleibt" 


IV 


YEAST  127 


the  very  singular  property  of  causing  alcohol  to 
change  into  acetic  acid  with  great  rapidity.  The 
vinegar  plant,  which  is  closely  allied  to  the  yeast 
plant,  has  a  similar  effect  upon  dilute  alcohol, 
causing  it  to  absorb  the  oxygen  of  the  air,  and 
become  converted  into  vinegar ;  and  Liebig's 
eminent  opponent,  Pasteur,  who  has  done  so  much 
for  the  theory  and  the  practice  of  vinegar-making, 
himself  suggests  that  in  this  case — 

*'La  cause  du  phenomene  physique  qui  accompagne  la  vie  de 
la  plante  reside  dans  un  etat  physique  propre,  analogue  k  celui 
du  noir  de  platine.  Mais  il  est  essentiel  de  remarquer  que  cet 
etat  physique  de  la  plante  est  etroitement  lie  avec  la  vie  de 
cette  plante."  ^ 

Now,  if  the  vinegar  plant  gives  rise  to  the  oxi- 
dation of  alcohol,  on  account  of  its  merely  phy- 
sical constitution,  it  is  at  any  rate  possible  that 
the  physical  constitution  of  the  yeast  plant  may 
exert  a  decomposing  influence  on  sugar. 

But,  without  presuming  to  discuss  a  question 
which  leads  us  into  the  very  arcana  of  chemistry, 
the  present  state  of  speculation  upon  the  modus 
operandi  of  the  yeast  plant  in  producing  fermenta- 
tion is  represented,  on  the  one  hand,  by  the 
Stahlian  doctrine,  supported  by  Liebig,  according 
to  which  the  atoms  of  the  sugar  are  shaken  into 
new  combinations,  either  directly  by  the  Torulce^ 
or  indirectly,  by  some  substance  formed  by  them ; 

*  Mvdes  mr  Us  Mycodfrmes,  Comptcs-Rendus,  liv.,  1862. 


128  YEAST  TV 

and,  on  the  other  hand,  by  the  Thunardian  doc- 
trine, supported  by  Pasteur,  according  to  which 
the  yeast  plant  assimilates  part  of  the  sugar,  and, 
in  so  doino^,  disturbs  the  rest,  and  determines  its 
resolution  into  the  products  of  fermentation.  Per- 
haps the  two  views  are  not  so  much  opposed  as 
they  seem  at  first  sight  to  be. 

But  the  interest  which  attaches  to  the  influence 
of  the  yeast  plants  upon  the  medium  in  which 
they  live  and  grow  does  not  arise  solely  from  its 
bearing  upon  the  theory  of  fermentation.  So  long 
ago  as  1838,  Turpin  compared  the  Torulce  to  the 
ultimate  elements  of  the  tissues  of  animals  and 
plants — "  Les  organes  elementaires  de  leurs  tissus, 
comparables  aux  petits  veg^taux  des  levures 
ordinaires,  sont  aussi  les  decompositeurs  des  sub- 
stances qui  les  environnent." 

Almost  at  the  same  time,  and,  probably,  equally 
guided  by  his  study  of  yeast,  Schwann  was  en- 
gaged in  those  remarkable  investigations  into  the 
form  and  development  of  the  ultimate  structural 
elements  of  the  tissues  of  animals,  Avhich  led  him 
to  recognise  their  fundamental  identity  with  the 
ultimate  structural  elements  of  vegetable  organ- 
isms. 

The  yeast  plant  is  a  mere  sac,  or  "  cell,"  con- 
taining a  semi-fluid  matter,  and  Schwann's  micro- 
scopic analysis  resolved  all  living  organisms,  in  the 
long  run,  into  an  aggregation  of  such  sacs  or  cells, 
variously  modified ;  and  tended  to  show,  that  all, 


rv 


YEAST  129 


whatever  their  ultimate  complication,  begin  their 
existence  in  the  condition  of  such  simple  cells. 

In  his  famous  "Mikroskopische  Untersuchun- 
gen  "  Schwann  speaks  of  Torula  as  a  "  cell  "  ;  and, 
in  a  remarkable  note  to  the  passage  in  which  he 
refers  to  the  yeast  plant,  Schwann  says : — 

**I  have  been  unable  to  avoid  mentioning  fermentation, 
because  it  is  the  most  fully  and  exactly  known  operation  of  cells, 
and  represents,  in  the  simplest  fashion,  the  process  which  is 
repeated  by  every  cell  of  the  living  body. " 

Jn  other  words,  Schwann  conceives  that  every 
cell  of  the  living  body  exerts  an  influence  on  the 
matter  which  surrounds  and  permeates  it,  ana- 
logous to  that  which  a  Tcrula  exerts  on  the 
saccharine  solution  by  which  it  is  bathed.  A 
wonderfully  suggestive  thought,  opening  up  views 
of  the  nature  of  the  chemical  processes  of  the 
living  body,  which  have  hardly  yet  received  all 
the  development  of  which  they  are  capable. 

Kant  defined  the  special  peculiarity  of  the  living 
body  to  be  that  the  parts  exist  for  the  sake  of  the 
whole  and  the  whole  for  the  sake  of  the  parts. 
But  when  Turpin  and  Schwann  resolved  the  living 
body  into  an  aggregation  of  quasi-independent 
cells,  each,  like  a  Torula,  leading  its  own  life  and 
having  its  own  laws  of  growth  and  development, 
the  aggregation  being  dominated  and  kept  work- 
ing towards  a  definite  end  only  by  a  certain 
harmony  among  these  units,  or  by  the  superaddition 

196 


130  YEAST  IV 

of  a  controlling  apparatus,  such  as  a  nervous  system, 
this  conception  ceased  to  be  tenable.  The  cell 
lives  for  its  own  sake,  as  well  as  for  the  sake  of 
the  whole  organism ;  and  the  cells  ivhich  float  in 
the  blood,  live  at  its  expense,  and  profoundly 
modify  it,  are  almost  as  much  independent  organ- 
isms as  the  Torulce  which  float  in  beer-wort. 

Schwann  burdened  his  enunciation  of  the  "  cell 
theory"  with  two  false  suppositions;  the  one, 
that  the  structures  he  called  "  nucleus  "  ^  and  "  cell- 
wall  "  are  essential  to  a  cell ;  the  other,  that  cells 
are  usually  formed  independently  of  other  cells ; 
but,  in  1839,  it  was  a  vast  and  clear  gain  to  arrive 
at  the  conception,  that  the  vital  functions  of  all 
the  higher  animals  and  plants  are  the  resultant  of 
the  forces  inherent  in  the  innumerable  minute  cells 
of  which  the}^  are  composed,  and  that  each  of  them 
is,  itself,  an  equivalent  of  one  of  the  lowest  and 
simplest  of  independent  living  beings — the  Torula, 

From  purely  morphological  investigations,  Tur- 
pin  and  Schwann,  as  we  have  seen,  arrived  at  the 
notion  of  the  fundamental  unity  of  structure  of 
living  beings.  And,  before  long,  the  researches  of 
chemists  gradually  led  up  to  the  conception  of  the 
fundamental  unity  of  their  composition. 

So  far  back  as  1803,  Thenard  pointed  out,  in 


^  [Later  investigations  have  thrown  an  entirely  new  light 
npon  the  structure  and  the  functional  importance  of  the 
nucleus  ;  and  have  proved  that  Schwann  did  not  over-estimate 
Its  iraportam^e.     1894.] 


rv  YEAST  131 

most  distinct  terms,  the  important  fact  that  yeast 
contains  a  nitrogenous  "  animal "  substance ;  and 
that  such  a  substance  is  contained  in  all  ferments. 
Before  him,  Fabroni  and  Fourcroy  speak  of  the 
"  vegeto-animal "  matter  of  yeast.  In  1844  Mulder 
endeavoured  to  demonstrate  that  a  peculiar  sub- 
stance, which  he  called  "  protein,"  was  essentially 
characteristic  of  living  matter. 
In  1846,  Payen  writes  : — 

"Enfin,  une  loi  sans  exception  me  semLle  apparaitre  dans 
les  faits  nombreux  que  j'ai  observes  et  conduire  a  envisager  sous 
un  nouveau  jour  la  vie  vegetale  ;  si  je  ne  m'abuse,  tout  ce  que 
dans  les  tissus  vegetaux  la  vue  directe  ou  amplitiee  nous  permet 
de  discerner  sous  la  forme  de  cellules  et  de  vaisseaux,  ne  represente 
autre  chose  que  les  enveloppes  protectrices,  les  reservoirs  et  les 
conduits,  a  I'aide  desquels  les  corps  animes  qui  les  secretent  et  les 
faQonnent,  se  logent,  puisent  et  charrient  leurs  aliments,  deposent 
et  isolent  les  matieres  excretees. " 

And  again : — 

"  Afin  de  completer  aujourd'hui  I'^nonce  du  fait  general,  je 
rappellerai  que  les  corps,  dou^  des  fonctions  accomplies  dans 
les  tissus  des  plantes,  sont  formes  des  elements  qui  constituent, 
en  proportion  peu  variable,  les  organismes  animaux  ;  qu'ainsi 
Ton  est  conduit  a  reconnaitre  une  immense  unite  de  composition 
^lementaire  dans  tous  les  corps  vivants  de  la  nature."  ^ 

In  the  year  (1846)  in  which  these  remarkable 
passages  were  published,  the  eminent  German 
botanist,  Yon  Mohl,  invented  the  word  "  proto- 
plasm," as  a  name  for  one  portion  of  those  nitro- 
genous contents  of  the  cells  of  living  plants,  the 

^  "Mem.  sur  les  Developpements  des  Vegetaux,'  &c. — Mim. 
Pri&cnUrs.  ix.   1846. 


132  YEAST  IV 

close  chemical  resemblance  of  which  to  the  essen- 
tial constituents  of  living  animals  is  so  strongly 
indicated  by  Payen.  And  through  the  twenty- 
five  years  that  have  passed,  since  the  matter  of 
life  was  first  called  protoplasm,  a  host  of  investi- 
gators, among  whom  Cohn,  Max  Schulze,  and 
Kiihne  must  be  named  as  leaders,  have  accum- 
ulated evidence,  morphological,  physiological,  and 
chemical,  in  favour  of  that  "  immense  unite  de 
composition  elementaire  dans  tous  les  corps  vivants 
de  la  nature,"  into  which  Payen  had,  so  early,  a 
clear  insight. 

As  far  back  as  1850,  Cohn  wrote,  apparently 
without  any  knowledge  of  what  Payen  had  said 
before  him : — 

"  The  protoplasm  of  the  botanist,  and  the  contractile  sub- 
stance and  sarcode  of  the  zoologist,  must  be,  if  notiientical,  yet 
in  a  high  degree  analogous  substances.  Hence,  fvom  this  point 
of  view,  the  difference  between  animals  and  plants  consists  in 
this  ;  that,  in  the  latter,  the  contractile  substance,  as  a  primordial 
utricle,  is  enclosed  within  an  inert  cellulose  membrane,  which 
permits  it  only  to  exhibit  an  internal  motion,  expressed  by  the 
phenomena  of  rotation  and  circulation,  while,  in  the  former,  it 
is  not  so  enclosed.  The  protoplasm  in  the  form  of  the  primordial 
utricle  is,  as  it  were,  the  animal  element  in  the  plant,  but 
which  is  imprisoned,  and  only  becomes  free  in  the  animal  ;  or, 
to  strip  off  the  metaphor  which  obscures  simple  thought,  the 
energy  of  organic  vitality  which  is  manifested  in  movement  is 
especially  exhibited  by  a  nitrogenous  contractile  substance, 
which  in  plants  is  limited  and  fettered  by  an  inert  membrane, 
in  animals  not  so."  ^ 

^  Cohn,  "Ueber  Protococcus  pluvialis, "  m  the  Nova  Acta  for 
1850. 


IV  YEAST  183 

In  1868,  thinking  that  an  untechnical  state- 
ment of  the  views  current  among  the  leaders  of 
biological  science  might  be  interesting  to  the 
general  public,  I  gave  a  lecture  embodpng  them  in 
Edinburgh.  Those  who  have  not  made  the  mis- 
take of  attempting  to  approach  biology,  either  by 
the  high  d,  priori  road  of  mere  philosophical  specu- 
lation, or  by  the  mere  low  a  posteriori  lane  offered 
by  the  tube  of  a  microscope,  but  have  taken  the 
trouble  to  become  acquainted  with  well-ascertained 
facts  and  with  their  history,  will  not  need  to 
be  told  that  in  what  I  had  to  say  "  as  regards 
protoplasm "  in  my  lecture  "  On  the  Physical 
Basis  of  Life  "  (Vol.  I.  of  these  Essays,  p.  130), 
there  was  nothing  new;  and,  as  I  hope,  no- 
thing that  the  present  state  of  knowledge  does 
not  justify  us  in  believing  to  be  true.  Under  these 
circumstances,  my  surprise  may  be  imagined,  when 
I  found,  that  the  mere  statement  of  facts  and  of 
views,  long  familiar  to  me  as  part  of  the  common 
scientific  property  of  Continental  workers,  raised  a 
sort  of  storm  in  this  country,  not  only  by  exciting 
the  wrath  of  unscientific  persons  whose  pet  pre- 
judices they  seemed  to  touch,  but  by  giving  rise  to 
quite  superfluous  explosions  on  the  part  of  some 
who  should  have  been  better  informed. 

Dr.  Stirling,  for  example,  made  my  essay  the 
subject  of  a  special  critical  lecture,^  which  I  have 

1  Subsequently  published  under  the  title  of   "As  regards 
Protoplasm." 


134  YEAST  IV 

read  with  mucli  interest,  though,  I  confess,  the 
meaning  of  much  of  it  remains  as  dark  to  me  as 
does  the  "  Secret  of  Hegel  "  after  Dr.  Stirhng's 
elaborate  revelation  of  it.  Dr.  Stirhng's  method 
of  dealing  with  the  subject  is  peculiar.  "  Proto- 
plasm "  is  a  question  of  history,  so  far  as  it  is  a 
name ;  of  fact,  so  far  as  it  is  a  thing.  Dr.  Stirling 
has  not  taken  the  trouble  to  refer  to  the  original 
authorities  for  his  history,  which  is  consequently  a 
travesty ;  and  still  less  has  he  concerned  himself 
with  looking  at  the  facts,  but  contents  himself 
with  taking  them  also  at  second-hand.  A  most 
amusing  example  of  this  fashion  of  dealing  with 
scientific  statements  is  furnished  by  Dr.  Stirling's 
remarks  upon  my  account  of  the  protoplasm  of  the 
nettle  hair.  That  account  was  drawn  up  from 
careful  and  often-repeated  observation  of  the  facts. 
Dr.  Stirling  thinks  he  is  offering  a  valid  criticism, 
when  he  says  that  my  valued  friend  Professor 
Strieker  gives  a  somewhat  different  statement 
about  protoplasm.  But  why  in  the  world  did  not 
this  distinguished  Hegelian  look  at  a  nettle  hair  for 
himself,  before  venturing  to  speak  about  the  matter 
at  all  ?  Why  trouble  himself  about  what  either 
Strieker  or  I  say,  when  any  t}TO  can  see  the  facts 
for  himself,  if  he  is  provided  with  those  not  rare 
articles,  a  nettle  and  a  microscope  ?  But  I  suppose 
this  would  have  been '' Avfkldrung  " — a  recurrence 
to  the  base  common-sense  philosophy  of  the 
eighteenth  century,  which  liked  to  see  before  it 


IV  YEAST  135 

believed,  and  to  understand  before  it  criiicised 
Dr.  Stirling  winds  up  his  paper  with  the  following 
paragraph : — 

"In  shovt,  the  whole  position  of  Mr.  Huxley,  (1)  that  all 
organisms  consist  alike  of  the  same  life-matter,  (2)  which  life- 
matter  is,  for  its  part,  due  only  to  chemistry,  must  be  pro- 
nounced untenable — nor  less  untenable  (3)  the  materialism  he 
•would  found  on  it." 

The  paragraph  contains  three  distinct  assertions 
concerning  my  views,  and  just  the  same  number  of 
utter  misrepresentations  of  them.  That  which  I 
have  numbered  (1)  turns  on  the  ambiguity  of  the 
word  "  same,"  for  a  discussion  of  which  I  would 
refer  Dr.  Stirling  to  a  great  hero  of  ''Aufkldrung" 
Archbishop  Whately ;  statement  number  (2)  is, 
in  my  judgment,  absurd,  and  certainly  I  have  never 
said  anything  resembling  it ;  while,  as  to  number 
(3),  one  great  object  of  my  essay  was  to  show  that 
what  is  called  "  materialism  "  has  no  sound  philo- 
sophical basis ! 

As  we  have  seen,  the  study  of  yeast  has  led  in- 
vestigators face  to  face  with  problems  of  immense 
interest  in  pure  chemistry,  and  in  animal  and 
vegetable  morphology.  Its  physiology  is  not  less 
rich  in  subjects  for  inquiry.  Take,  for  example, 
the  singular  fact  that  yeast  will  increase  indefin- 
itely when  grown  in  the  dark,  in  water  containing 
only  tartrate  of  ammonia,  a  small  percentage  of 
mineral  salts,  and  sugar.  Out  of  these  materials 
the  Torulce  will  manufacture  nitrogenous  proto- 


136  YEAST  IV 

plasm,  cellulose,  and  fatty  matters,  in  any  quantity, 
although  they  are  wholly  deprived  of  those  rays  of 
the  sun,  the  influence  of  which  is  essential  to  the 
growth  of  ordinary  plants.  There  has  been  a 
great. deal  of  speculation  lately,  as  to  how  the 
living  organisms  buried  beneath  two  or  three 
thousand  fathoms  of  water,  and  therefore  in  all 
probability  almost  deprived  of  light,  live.  If  any 
of  them  possess  the  same  powers  as  yeast  (and 
the  same  capacity  for  living  without  light  is  ex- 
hibited by  some  other  fungi)  there  would  seem  to 
be  no  difficulty  about  the  matter. 

Of  the  pathological  bearings  of  the  study  of 
yeast,  and  other  such  organisms,  I  have  spoken 
elsewhere.  It  is  certain  that,  in  some  animals, 
devastating  epidemics  are  caused  by  fungi  of  low 
order — similar  to  those  of  which  Too-ula  is  a  sort 
of  offshoot.  It  is  certain  that  such  diseases  are 
propagated  by  contagion  and  infection,  in  just 
the  same  way  as  ordinary  contagious  and  infectious 
diseases  are  propagated.  Of  course,  it  does  not 
follow  from  this,  that  all  contagious  and  infectious 
diseases  are  caused  by  organisms  of  as  definite 
and  independent  a  character  as  the  Toritla ;  but, 
I  think,  it  does  follow  that  it  is  prudent  and  wise 
to  satisfy  one's  self  in  each  particular  case,  that  the 
"germ  theory"  cannot  and  will  not  explain  the 
facts,  before  having  recourse  to  hypotheses  which 
have  no  equal  support  from  analogy. 


ON  THE  FORMATION  OF  COAL 

[1870] 

The  lumps  of  coal  in  a  coal-scuttle  very  often 
have  a  roughly  cubical  form.  If  one  of  them  be 
picked  out  and  examined  with  a  little  care,  it  wiU 
be  found  that  its  six  sides  are  not  exactly  alike. 
Two  opposite  sides  are  comparatively  smooth  and 
shining,  while  the  other  four  are  much  rougher, 
and  are  marked  by  lines  which  run  parallel  with 
the  smooth  sides.  The  coal  readily  splits  along 
these  lines,  and  the  split  surfaces  thus  formed 
are  parallel  with  the  smooth  faces.  In  other 
words,  there  is  a  sort  of  rough  and  incomplete 
stratification  in  the  lump  of  coal,  as  if  it  were  a 
book,  the  leaves  of  which  had  stuck  together  very 
closely. 

Sometimes  the  faces  along  which  the  coal  splits 
are  not  smooth,  but  exhibit  a  thin  layer  of  dull, 
charred-looking  substance,  which  is  known  a3 
"  mineral  charcoal" 


138  ON   THE   FORMATION   OF   COAL  v 

Occasionally  one  of  tlie  faces  of  a  lump  of  coal 
will  present  impressions,  which  are  obviously 
those  of  the  stem,  or  leaves,  of  a  plant ;  but 
though  hard  mineral  masses  of  p}Tites,  and  even 
fine  mud,  may  occur  here  and  there,  neither  sand 
nor  pebbles  are  met  with. 

When  the  coal  burns,  the  chief  ultimate 
products  of  its  combustion  are  carbonic  acid, 
water,  and  ammoniacal  products,  which  escape 
up  the  chimney ;  and  a  greater  or  less  amount 
of  residual  earthy  salts,  which  take  the  form  of 
ash.  These  products  are,  to  a  great  extent,  such 
as  would  result  from  the  burning  of  so  much 
wood. 

These  properties  of  coal  may  be  made  out 
without  any  very  refined  appliances,  but  the 
microscope  reveals  something  more.  Black  and 
opaque  as  ordinary  coal  is,  slices  of  it  become 
transparent  if  they  are  cemented  in  Canada 
balsam,  and  rubbed  dovni  very  thin,  in  the 
ordinary  way  of  making  thin  sections  of  non- 
transparent  bodies.  But  as  the  thin  slices,  made 
in  this  way,  are  very  apt  to  crack  and  break 
into  fragments,  it  is  better  to  employ  marine 
glue  as  the  cementing  material.  By  the  use  of 
this  substance,  slices  of  considerable  size  and 
of  extreme  thinness  and  transparency  may  be 
obtained.^ 

^  My  assistant  in  the  Museum  of  Practical  Geolo^,  Mr. 
Newton,  invented  this  excellent  method  of  obtaining  thin  slices 
of  coal. 


V  ON   THE   FORMATION   OF   COAL  139 

Now  let  us  suppose  two  such  slices  to  be 
prepared  from  our  lump  of  coal — one  parallel 
with  the  bedding,  the  other  perpendicular  to  it ; 
and  let  us  call  the  one  the  horizontal,  and  the 
other  the  vertical,  section.  The  horizontal  section 
will  present  more  or  less  rounded  yellow  patches 
and  streaks,  scattered  irregularly  tlirough  the 
dark  brown,  or  blackish,  ground  substance ;  while 
the  vertical  section  will  exhibit  mere  elongated 
bars  and  granules  of  the  same  yellow  materials, 
disposed  in  lines  which  correspond,  roughly,  with 
the  general  direction  of  the  bedding  of  the  coal. 

This  is  the  microscopic  structure  of  an  ordinary- 
piece  of  coal.  But  if  a  great  series  of  coals,  from 
different  locahties  and  seams,  or  even  from 
different  parts  of  the  same  seam,  be  examined, 
this  structure  will  be  found  to  vary  in  two 
directions.  In  the  anthracitic,  or  stone-coals,  which 
burn  like  coke,  the  yellow  matter  diminishes, 
and  the  ground  substance  becomes  more  pre- 
dominant, blacker,  and  more  opaque,  until  it  be- 
comes impossible  to  grind  a  section  thin  enough 
to  be  translucent ;  while,  on  the  other  hand,  in 
such  as  the  "  Better-Bed  "  coal  of  the  neigfhbour- 
hood  of  Bradford,  which  burns  with  much  flame, 
the  coal  is  of  a  far  lighter  colour,  and  transparent 
sections  are  very  easily  obtained.  In  the  browner 
parts  of  this  coal,  sharp  eyes  will  readily  detect 
multitudes  of  curious  little  coin-shaped  bodies, 
of  a  yellowish   brown   colour,  embedded  in   the 


140  ON   THE   FORMATION   OF  COAL  v 

dark  brown  ground  substance.  On  the  average, 
these  httle  brown  bodies  may  have  a  diameter  of 
about  one-twentieth  of  an  inch.  They  he  with 
their  flat  surfaces  nearly  parallel  with  the  two 
smooth  faces  of  the  block  in  which  they  are  con- 
tained ;  and,  on  one  side  of  each,  there  may  be 
discerned  a  figure,  consisting  of  three  straight 
linear  marks,  which  radiate  from  the  centre  of 
the  disk,  but  do  not  quite  reach  its  circumference. 
In  the  horizontal  section  these  disks  are  often 
converted  into  more  or  less  complete  rings  ;  while 
in  the  vertical  sections  they  appear  hke  thick 
hoops,  the  sides  of  which  have  been  pressed  to- 
gether. The  disks  are,  therefore,  flattened  bags ; 
and  favourable  sections  show  that  the  three-rayed 
marking  is  the  expression  of  three  clefts,  which 
penetrate  one  wall  of  the  bag. 

The  sides  of  the  bags  are  sometimes  closely 
approximated ;  but,  when  the  bags  are  less 
flattened,  their  cavities  are,  usually,  filled  wdth 
numerous,  irregularly  rounded,  hollow  bodies, 
having  the  same  kind  of  wall  as  the  large  ones, 
but  not  more  than  one  seven-hundredth  of  an 
inch  in  diameter. 

In  favourable  specimens,  again,  almost  the 
whole  ground  substance  appears  to  be  made  up 
of  similar  bodies — more  or  less  carbonized  or 
blackened — and,  in  these,  there  can  be  no  doubt 
that,  with  the  exception  of  patches  of  mineral 
charcoal,  here  and  there,  the  whole  mass  of  the 


V  ON   THE   FORMATION  OF  COAL  141 

coal  IS  made  up  of  an  accumulation  of  the  larger 
and  of  the  smaller  sacs. 

But,  in  one  and  the  same  slice,  every  transition 
can  be  observed  from  this  structure  to  that  which 
has  been  described  as  characteristic  of  ordinary 
coal.  The  latter  appears  to  rise  out  of  the 
former,  by  the  breaking-up  and  increasing  car- 
bonization of  the  larger  and  the  smaller  sacs. 
And,  in  the  anthracitic  coals,  this  process  appears 
to  have  gone  to  such  a  length,  as  to  destroy  the 
original  structure  altogether,  and  to  replace  it  by 
a  completely  carbonized  substance. 

Thus  coal  may  be  said,  speaking  broadly,  to  be 
composed  of  two  constituents :  firstly,  mineral 
charcoal ;  and,  secondly,  coal  proper.  The  nature 
of  the  mineral  charcoal  has  long  since  been 
determined.  Its  structure  shows  it  to  consist  of 
the  remains  of  the  stems  and  leaves  of  plants, 
reduced  a  little  more  than  their  carbon.  Again, 
some  of  the  coal  is  made  up  of  the  crushed  and 
flattened  bark,  or  outer  coat,  of  the  stems  of  plants, 
the  inner  wood  of  which  has  completely  decayed 
away.  But  what  I  may  term  the  "saccular 
matter  "  of  the  coal,  which,  either  in  its  primary 
or  in  its  degraded  form,  constitutes  by  far  the 
greater  part  of  all  the  bituminous  coals  I  have 
examined,  is  certainly  not  mineral  charcoal ;  nor 
is  its  structure  that  of  any  stem  or  leaf  Hence 
its  real  nature  is,  at  first,  by  no  means  appai-ent, 
and  has  been  the  subject  of  much  discussion. 


142  ON   THE   FORMATION   OF   COAL  v 

The  first  person  who  threw  any  light  upon  the 
problem,  as  far  as  I  have  been  able  to  discover, 
was  the  well-known  geologist,  Professor  Morris. 
It  is  now  thirty-four  years  since  he  carefully 
described  and  figured  the  coin-shaped  bodies,  or 
larger  sacs,  as  I  have  called  them,  in  a  note 
appended  to  the  famous  paper  "  On  the  Coal- 
brookdale  Coal-Field,"  published  at  that  time, 
by  the  present  President  of  the  Geological  Society, 
Mr.  Prestwich.  With  much  sagacity,  Professor 
Morris  divined  the  real  nature  of  these  bodies. 
and  boldly  affirmed  them  to  be  the  spore-cases 
of  a  plant  allied  to  the  living  club-mosses. 

But  discovery  sometimes  makes  a  long  halt ; 
and  it  is  only  a  few  years  since  Mr.  Carruthers 
determined  the  plant  (or  rather  one  of  the  plants) 
which  produces  these  spore-cases,  by  finding  the 
discoidal  sacs  still  adherent  to  the  leaves  of  the 
fossihzed  cone  which  produced  them.  He  gave 
the  name  of  Flemingites  gracilis  to  the  plant  of 
which  the  cones  form  a  part.  The  branches 
and  stem  of  this  plant  are  not  yet  certainly 
known,  but  there  is  no  sort  of  doubt  that  it  was 
closely  allied  to  the  Leioidcdcndron,  the  remains 
of  which  abound  in  the  coal  formation.  The 
Zepidodendra  were  shrubs  and  trees  which  put 
one  more  in  mind  of  an  Araucaria  than  of  any 
other  familiar  plant ;  and  the  ends  of  the  fruiting 
branches  were  terminated  by  cones,  or  catkins, 
somewhat  like  the  bodies  so  named  in  a  fir,  or  a 


y  ON  THE   FORMATION  OF  COAL  .143 

willow.  TheS3  conical  fruits,  however,  did  not 
produce  seeds ;  but  the  leaves  of  which  they 
were  composed  bore  upon  their  surfaces  sacs  full 
of  spores  or  sporangia,  such  as  those  one  sees  on 
the  under  surface  of  a  bracken  leaf  Now,  it  is 
these  sporangia  of  the  Lepidodendroid  plant 
Flemingites  which  were  identified  by  Mr.  Carruthers 
with  the  free  sporangia  described  by  Professor 
Morris,  which  are  the  same  as  the  large  sacs  of 
which  I  have  spoken.  And,  more  than  this, 
there  is  no  doubt  that  the  small  sacs  are  the 
spores,  which  were  originally  contained  in  the 
sporangia. 

The  living  club-mosses  are,  for  the  most  part, 
insignificant  and  creeping  herbs,  which,  super- 
ficially, very  closely  resemble  true  mosses,  and 
none  of  them  reach  more  than  two  or  three  feet 
in  height.  But,  in  their  essential  structure,  they 
very  closely  resemble  the  earliest  Lepidodendroid 
trees  of  the  coal :  their  stems  and  leaves  are 
similar ;  so  are  their  cones ;  and  no  less  hke  are 
the  sporangia  and  spores ;  while  even  in  their 
size,  the  spores  of  the  Lepidodendron  and  those  of 
the  existing  Lycopodium,  or  club-moss,  very  closely 
approach  one  another. 

Thus,  the  singular  conclusion  is  forced  upon  us, 
that  the  greater  and  the  smaller  sacs  of  the 
"Better-Bed"  and  other  coals,  in  which  the 
primitive  structure  is  well  preserved,  are  simply 
the  sporangia  and  spores  of  certain  plants,  many 


144  ON   THE   FORMATION   OF   COAL  v 

of  whicli  were  closely  allied  to  tlie  existing  club- 
mosses.  And  if,  as  I  believe,  it  can  be  demon- 
strated that  ordinary  coal  is  nothing  but 
"  saccular "  coal  which  has  undergone  a  certain 
amount  of  that  alteration  which,  if  continued, 
would  convert  it  into  anthracite ;  then,  the  con- 
clusion is  obvious,  that  the  great  mass  of  the 
coal  we  burn  is  the  result  of  the  accumulation  of 
the  spores  and  spore-cases  of  plants,  other  parts  of 
which  have  furnished  the  carbonized  stems  and 
the  mineral  charcoal,  or  have  left  their  impressions 
on  the  surfaces  of  the  layer. 

Of  the  multitudinous  speculations  which,  at 
various  times,  have  been  entertained  respecting 
the  origin  and  mode  of  formation  of  coal,  several 
appear  to  be  negatived,  and  put  out  of  court,  by 
the  structural  facts  the  significance  of  which  I 
have  endeavoured  to  explain.  These  facts,  for 
example,  do  not  permit  us  to  suppose  that  coal  is 
an  accumulation  of  peaty  matter,  as  some  have 
held. 

Again,  the  late  Professor  Quekett  was  one  of 
the  first  observers  who  gave  a  correct  description 
of  what  I  have  termed  the  "  saccular "  structure 
of  coal ;  and,  rightly  perceiving  that  this  structure 
was  something  quite  different  from  that  of  any 
known  plant,  he  imagined  that  it  proceeded  fi-om 
some  extinct  vegetable  organism  which  was 
peculiarly  abundant  amongst  the  coal-forming 
plants.     But  this  explanation  is  at  once  shown  to 


V  ON   THE   FORMATION   OF   COAL  145 

be  untenable  when  the  smaller  and  the  larger  sacs 
are  proved  to  be  spores  or  sporangia. 

Some,  once  more,  have  imagined  that  coal  was 
of  submarine  origin;  and  though  the  notion  is 
amply  and  easily  refuted  by  other  considerations, 
it  may  be  worth  while  to  remark,  that  it  is 
impossible  to  comprehend  how  a  mass  of  light 
and  resinous  spores  should  have  reached  the 
bottom  of  the  sea,  or  should  have  stopped  in  that 
position  if  they  had  got  there. 

At  the  same  time,  it  is  proper  to  remark  that  I 
do  not  presume  to  suggest  that  all  coal  must 
needs  have  the  same  structure ;  or  that  there  may 
not  be  coals  in  which  the  proportions  of  wood  and 
spores,  or  spore-cases,  are  very  different  from  those 
which  I  have  examined.  All  I  repeat  is,  that 
none  of  the  coals  which  have  come  under  my 
notice  have  enabled  me  to  observe  such  a  dif- 
ference. But,  according  to  Principal  Dawson,  who 
has  so  sedulously  examined  the  fossil  remains 
of  plants  in  North  America,  it  is  otherwise 
with  the  vast  accumulations  of  coal  in  that 
country. 

"The  true  coal.,"  says  Dr.  Dawson,  "consists  principally  of 
the  flattened  bark  of  Sigillarioid  and  other  trees,  intermixed 
with  leaves  of  Ferns  and  Cordaites,  and  other  herbaceous  debris, 
and  with  fragments  of  decayed  wood,  constituting  '  mineral  char- 
coal,' all  these  materials  having  manifestly  alike  grown  and 
accumulated  where  we  find  them."  ^ 


^  Acadian  Geology,  2nd  edition,  p.  138. 
196 


146  ON   THE   FORMATION   OF   COAL  y 

When  I  had  the  pleasure  of  seeing  Principal 
Dawson  in  London  last  summer,  I  showed  him 
my  sections  of  coal,  and  begged  him  to  re-examine 
some  of  the  American  coals  on  his  return  to 
Canada,  with  an  eye  to  the  presence  of  spores  and 
sporangia,  such  as  I  was  able  to  show  him  in  our 
English  and  Scotch  coals.  He  has  been  good 
enough  to  do  so ;  and  in  a  letter  dated  September 
26th,  1870,  he  informs  me  that — 

"  Indications  of  spore-cases  are  rare,  except  in  certain  coarse 
shaly  coals  and  portions  of  coals,  and  in  the  roofs  of  the  seams. 
The  most  marked  case  I  have  yet  met  with  is  the  shaly  coal 
referred  to  as  containing  Sporavgitrs  in  my  paper  on  the  con- 
ditions of  accumulation  of  coal  ('*  Journal  of  the  Geological 
Society,"  vol.  xxii.  pp.  115,  139,  and  165).  The  purer  coals  cer- 
tainly consist  principally  of  cubical  tissues  with  some  true  woody 
matter,  and  the  spore-cases,  &c.,  are  chiefly  in  the  coarse  and 
shaly  layers.  This  is  my  old  doctrine  in  my  two  papers  in  the 
"  Journal  of  the  Geological  Society,"  and  I  see  nothing  to  modify 
it.  Your  observations,  however,  make  it  probable  that  the 
frequent  dear  s2Juts  in  the  cannels  are  spore-cases. " 

Dr.  Dawson's  results  are  the  more  remarkable, 
as  the  numerous  specimens  of  British  coal,  from 
various  localities,  which  I  have  examined,  tell  one 
tale  as  to  the  predominance  of  the  spore  and 
sporangium  element  in  their  composition ;  and  as 
it  is  exactly  in  the  finest  and  purest  coals,  such  as 
the  "Better-Bed"  coal  of  Lowmoor,  that  the 
spores  and  sporangia  obviously  constitute  almost 
the  entire  mass  of  the  deposit. 

Coal,  such  as  that  which  has  been  described,  is 


V  ON   THE   FORMATION   OF   COAL  147 

always  found  in  sheets,  or  "  seams,"  varying  from 
a  fraction  of  an  inch  to  many  feet  in  thickness, 
enclosed  in  the  substance  of  the  earth  at  very 
various  depths,  between  beds  of  rock  of  different 
kinds.  As  a  rule,  every  seam  of  coal  rests  upon  a 
thicker,  or  thinner,  bed  of  clay,  which  is  known 
as  "  under-clay."  These  alternations  of  beds  of 
coal,  clay,  and  rock  may  be  repeated  many  times, 
and  are  known  as  the  "  coal-measures " ;  and  in 
some  regions,  as  in  South  Wales  and  in  Nova 
Scotia,  the  coal-measures  attain  a  thickness  of 
twelve  or  fourteen  thousand  feet,  and  enclose 
eighty  or  a  hundred  seams  of  coal,  each  with  its 
under-clay,  and  separated  from  those  above  and 
below  by  beds  of  sandstone  and  shale. 

The  position  of  the  beds  which  constitute  the 
coal-measures  is  infinitely  diverse.  Sometimes 
they  are  tilted  up  vertically,  sometimes  they  are 
horizontal,  sometimes  curved  into  gi^eat  basins; 
sometimes  they  come  to  the  surface,  sometimes 
they  are  covered  up  by  thousands  of  feet  of  rock. 
But,  whatever  their  present  position,  there  is 
abundant  and  conclusive  evidence  that  every 
under-clay  was  once  a  surface  soil.  Not  only  do 
carbonized  root-fibres  frequently  abound  in  these 
under-clays ;  but  the  stools  of  trees,  the  trunks  of 
which  are  broken  off  and  confounded  with  the  bed 
of  coal,  have  been  repeatedly  found  passing  into 
radiating  roots,  still  embedded  in  the  under-clay. 
On  many  parts  of  the  coast  of  England,  what  are 


148  ON   THE   FORMATION   OF  COAL  v 

commonly  known  as  "  submarine  forests "  are  to 
be  seen  at  low  water.  They  consist,  for  the  most 
part,  of  short  stools  of  oak,  beech,  and  fir-trees, 
still  fixed  by  their  long  roots  in  the  bed  of  blue 
clay  in  which  they  originally  grew.  If  one  of 
these  submarine  forest  beds  should  be  gradually 
depressed  and  covered  up  by  new  deposits,  it 
would  present  just  the  same  characters  as  an 
under-clay  of  the  coal,  if  the  Sigillaria  and 
LcioiclGdendron  of  the  ancient  world  were  sub- 
stituted for  the  oak,  or  the  beech,  of  our  own 
times. 

In  a  tropical  forest,  at  the  present  day,  the 
trunks  of  fallen  trees,  and  the  stools  of  such  trees 
as  may  have  been  broken  by  the  violence  of 
storms,  remain  entire  for  but  a  short  time.  Con- 
trary to  what  might  be  expected,  the  dense  wood 
of  the  tree  decays,  and  suffers  from  the  ravages  of 
insects,  more  swiftly  than  the  bark.  And  the 
traveller,  setting  his  foot  on  a  prostrate  trunk, 
finds  that  it  is  a  mere  shell,  which  breaks  under 
his  weight,  and  lands  his  foot  amidst  the  insects, 
or  the  reptiles,  which  have  sought  food  or  refuge 
within. 

The  trees  of  the  coal  forests  present  parallel 
conditions.  When  the  fallen  trunks  which  have 
entered  into  the  composition  of  the  bed  of  coal 
are  identifiable,  they  are  mere  double  shells  of 
bark,  flattened  together  in  consequence  of  the 
destruction  of  the  woody  core;  and  Sir  Charles 


V  ON   THE   FORMATION    OF   COAL  149 

Lyell  and  Principal  Dawson  discovered,  in  the 
hollow  stools  of  coal  trees  of  Nova  Scotia,  the 
remains  of  snails,  millipedes,  and  salamander-like 
creatures,  embedded  in  a  deposit  of  a  different 
character  from  that  which  surrounded  the  exterior 
of  the  trees.  Thus,  in  endeavouring  to  compre- 
hend the  formation  of  a  seam  of  coal,  we  must  try 
to  picture  to  ourselves  a  thick  forest,  formed  for 
the  most  part  of  trees  like  gigantic  club-mosses, 
mares'-tails,  and  tree-ferns,  with  here  and  there 
some  that  had  more  resemblance  to  our  existing 
yews  and  fir-trees.  We  must  suppose  that,  as  the 
seasons  rolled  by,  the  plants  grew  and  developed 
their  spores  and  seeds;  that  they  shed  these  in 
enormous  quantities,  which  accumulated  on  the 
ground  beneath ;  and  that,  every  now  and  then, 
they  added  a  dead  frond  or  leaf;  or,  at  longer 
intervals,  a  rotten  branch,  or  a  dead  trunk,  to 
the  mass. 

A  certain  proportion  of  the  spores  and  seeds  no 
doubt  fulfilled  their  obvious  function,  and,  car- 
ried by  the  wind  to  unoccupied  regions,  ex- 
tended the  limits  of  the  forest ;  many  might  be 
washed  away  by  rain  into  streams,  and  be  lost ; 
but  a  large  portion  must  have  remained,  to 
accumulate  like  beech-mast,  or  acorns,  beneath 
the  trees  of  a  modern  forest. 

But,  in  this  case,  it  may  be  asked,  why  does 
not  our  English  coal  consist  of  stems  and  leaves 
to  a  much  greater  extent  than  it  does  ?     What  is 


150  ON   THE   FORMATION   OF   COAL  > 

the  reason  of  the  predominance  of  the  spores  and 
spore-cases  in  it  ? 

A  ready  answer  to  this  question  is  afforded  hy 
the  study  of  a  h  ving  full-grown  club-moss.  Shake  it 
upon  a  piece  of  paper,  and  it  emits  a  cloud  of  fine 
dust,  which  falls  over  the  paper,  and  is  the  well- 
known  Lycopodium  powder.  Now  this  powder 
used  to  be,  and  I  believe  still  is,  employed  for  two 
objects  which  seem,  at  first  sight,  to  have  no  par- 
ticular connection  with  one  another.  It  is,  or  was, 
employed  in  making  lightning,  and  in  making 
pills.  The  coats  of  the  spores  contain  so  much 
resinous  matter,  that  a  pinch  of  Lycopodium  pow- 
der, thrown  through  the  flame  of  a  candle,  burns 
with  an  instantaneous  flash,  which  has  long  done 
duty  for  lightning  on  the  stage.  And  the  same 
character  makes  it  a  capital  coating  for  pills ;  for 
the  resinous  powder  prevents  the  drug  from  being 
wetted  by  the  saliva,  and  thus  bars  the  nauseous 
flavour  from  the  sensitive  papillae  of  the  tongue. 

But  this  resinous  matter,  which  lies  in  the  walls 
of  the  spores  and  sporangia,  is  a  substance  not 
easily  altered  by  air  and  water,  and  hence  tends 
to  preserve  these  bodies,  just  as  the  bituminized 
cerecloth  preserves  an  Egyptian  mummy ;  while, 
on  the  other  hand,  the  merely  woody  stem  and 
leaves  tend  to  rot,  as  fast  as  the  wood  of  the 
mummy's  coffin  has  rotted.  Thus  the  mixed  heap 
of  spores,  leaves,  and  stems  in  the  coal-forest  would 
be   persistently   searched   by  the  long-continued 


y  ON   THE   FORMATION   OF   COAL  151 

action  of  air  and  rain ;  the  leaves  and  stems  would 
gradually  be  reduced  to  little  but  their  carbon,  or, 
in  other  words,  to  the  condition  of  mineral  char- 
coal in  which  we  find  them ;  while  the  spores  and 
sporangia  remained  as  a  comparatively  unaltered 
and  compact  residuum. 

There  is,  indeed,  tolerably  clear  evidence  that 
the  coal  must,  under  some  circumstances,  have 
been  converted  into  a  substance  hard  enough  to 
be  rolled  into  pebbles,  while  it  yet  lay  at  the 
surface  of  the  earth;  for  in  some  seams  of  coal, 
the  courses  of  rivulets,  which  must  have  been 
living  water,  while  the  stratum  in  which  their 
remains  are  found  was  still  at  the  surface,  have 
been  observed  to  contain  rolled  pebbles  of  the 
very  coal  through  which  the  stream  has  cut  its 
way. 

The  structural  facts  are  such  as  to  leave  no 
alternative  but  to  adopt  the  view  of  the  origin 
of  such  coal  as  I  have  described,  which  has  just 
been  stated ;  but,  happily,  the  process  is  not 
without  analogy  at  the  present  day.  I  possess  a 
specimen  of  what  is  called  "white  coal"  from 
Australia.  It  is  an  inflammable  material,  burning 
with  a  bright  flame,  and  having  much  the  con- 
sistence and  appearance  of  oat-cake,  which,  I  am 
informed,  covers  a  considerable  area.  It  consists, 
almost  entirely,  of  a  compacted  mass  of  spores  and 
spore-cases.  But  the  fine  particles  of  blown  sand 
which  are  scattered  through  it,  show  that  it  must 


152  ON   THE   FORMATION   OF   COAL  y 

have  accumulated,  subaerially,  upon  the  surface 
of  a  soil  covered  by  a  forest  of  cryptogamous 
plants,  probably  tree-ferns. 

As  regards  this  important  point  of  the  subaerial 
region  of  coal,  I  am  glad  to  find  myself  in  entire 
accordance  with  Principal  Dawson,  who  bases  his 
conclusions  upon  other,  but  no  less  forcible, 
considerations.  In  a  passage,  which  is  the  con- 
tinuation of  that  already  cited,  he  writes  : — 

*''(3)  The  microscopical  structure  and  chemical  composition 
of  the  beds  of  cannel  coal  and  earthy  bitumen,  and  of  the  more 
highly  bituminous  and  carbonaceous  shale,  show  them  to  have 
been  of  the  nature  of  the  fine  vegetable  mudwliich  accumulates 
in  the  ponds  and  shallow  lakes  of  modern  swamps.  "When  such 
fine  vegetable  sediment  is  mixed,  as  is  often  the  case,  with  clay, 
it  becomes  similar  to  the  bituminous  limestone  and  calcareo- 
bituminous  shales  of  the  coal-measures.  (4)  A  few  of  the  under- 
clays,  which  support  beds  of  coal,  are  of  the  nature  of  the  vege- 
table mud  above  referred  to  ;  but  the  greater  part  are  argillo- 
arenaceous  in  composition,  with  little  vegetable  matter,  and 
bleaclied  by  the  drainage  from  them  of  water  containing  the 
products  of  vegetable  decay.  They  are,  in  short,  loamy  or  clay 
soils,  and  must  have  been  sufficiently  above  water  to  admit  of 
drainage.  The  absence  of  sul[>hurets,  and  the  occurrence  of 
carbonate  of  iron  in  connection  with  them,  prove  that,  when 
they  existed  as  soils,  rain-water,  and  not  sea-water,  percolated 
them.  (5)  The  coal  and  the  fossil  forests  present  many  evi- 
dences of  subaerial  conditions.  Most  of  the  erect  and  prostrate 
trees  had  become  hollow  shells  of  bark  before  they  were  finally 
embedded,  and  their  wood  had  broken  into  cubical  pieces  of 
mineral  charcoal.  Land-snails  and  galley-worms  (Xyl(>h!us) 
crept  into  them,  and  they  became  dens,  or  traps,  for  reptiles. 
Large  quantities  of  mineral  charcoal  occur  on  the  surface  of  all 
the  large  beds  of  coal.  None  of  these  appearances  could  have 
been  produced  by  subaqueous  action.     (6)  Though  the  roots  of 


V  ON    THE   FORMATION   OF   COAL  153 

the  Sigillaria  bear  more  resemblance  to  the  rhizomes  of  certain 
aquatic  plants  ;  yet,  structurally,  they  are  absolutely  identical 
with  the  roots  of  Cycads,  which  the  stems  also  resemble. 
Further,  the  Sigillarice  grew  on  the  same  soils  which  supported 
Conifers,  Lrpidodendra,  Cordaites,  and  Ferns — plants  which 
could  not  have  grown  in  water.  Again,  with  the  exception 
perhaps  of  some  Pinnularice  and  Aster ophyllites,  there  is  a 
remarkable  absence  from  the  coal  measures  of  any  form  of 
properly  aquatic  vegetation.  (7)  The  occurrence  of  marine,  or 
brackish -water  animals,  in  the  roofs  of  coal-beds,  or  even  in  the 
coal  itself,  affords  no  evidence  of  subaqueous  accumulation, 
since  the  same  thing  occurs  in  the  case  of  modern  submarine 
forests.  For  these  and  otlier  reasons,  some  of  which  are  more 
fully  stated  in  the  papers  already  referred  to,  while  I  admit  that 
the  areas  of  coal  accumulation  were  frequently  submerged,  I 
must  maintain  that  the  true  coal  is  a  subaerial  accumulation  by 
vegetable  growth  on  soils,  wet  and  swampy  it  is  true,  but  not 
submerged. " 

I  am  almost  disposed  to  doubt  whether  it  is 
necessary  to  make  the  concession  of  "wet  and 
swampy  "  ;  otherwise,  there  is  nothing  that  I  know 
of  to  be  said  against  this  excellent  conspectus  of 
the  reasons  for  believinoj  in  the  subaerial  orimn  of 
coal. 

But  the  coal  accumulated  upon  the  area  covered 
by  one  of  the  great  forests  of  the  carboniferous 
epoch  would,  in  course  of  time,  have  been  wasted 
away  by  the  small,  bt  fc  constant,  wear  and  tear  of 
rain  and  streams,  had  the  land  which  supported  it 
remained  at  the  same  level,  or  been  gradually 
raised  to  a  greater  elevation.  And,  no  doubt,  aa 
much  coal  as  now  exists  has  been  destroyed,  after 
its  formation,  in  this  way.     What  are  now  known 


154  ON   THE   FORMATION   OF   COAL  v 

as  coal  districts  owe  their  importance  to  the  fact 
that  they  were  areas  of  slow  depression,  during  a 
greater  or  less  portion  of  the  carboniferous  epoch ; 
and  that,  in  virtue  of  this  circumstance,  Mother 
Earth  was  enabled  to  cover  up  her  vegetable 
treasures,  and  preserve  them  from  destruction. 

Wherever  a  coal-field  now  exists,  there  must 
formerly  have  been  free  access  for  a  great  river,  or 
for  a  shallow  sea,  bearing  sediment  in  the  shape  of 
sand  and  mud.  When  the  coal-forest  area  became 
slowly  depressed,  the  waters  must  have  spread 
over  it,  and  have  deposited  their  burden  upon  the 
surface  of  the  bed  of  coal,  in  the  form  of  layers, 
which  are  now  converted  into  shale,  or  sandstone. 
Then  followed  a  period  of  rest,  in  which  the 
superincumbent  shallow  waters  became  completely 
filled  up,  and  finally  replaced,  by  fine  mud,  which 
settled  down  into  a  new  under-clay,  and  furnished 
the  soil  for  a  fresh  forest  growth.  This  flourished, 
and  heaped  up  its  spores  and  wood  into  coal,  until 
the  stage  of  slow  depression  recommenced.  And, 
in  some  localities,  as  I  have  mentioned,  the  process 
was  repeated  until  the  first  of  the  alternating 
beds  had  sunk  to  near  three  miles  below  its 
oriofinal  level  at  the  surface  of  the  earth. 

In  reflecting  on  the  statement,  thus  briefly 
made,  of  the  main  facts  connected  with  the 
orimn  of  the  coal  formed  durinor  the  carboniferous 
epoch,  two  or  three  considerations  suggest  them- 
selves. 


V  ON    THE   FORMATION   OF  COAL  155 

In  the  first  place,  tlie  great  phantom  of  geo- 
logical time  rises  before  the  student  of  this,  as  of 
all  other,  fragments  of  the  history  of  our  earth — 
springing  irrepressibly  out  of  the  facts,  like  the 
Djin  from  the  jar  which  the  fishermen  so  incau- 
tiously opened  ;  and  like  the  Djin  again,  being 
vaporous,  shifting,  and  indefinable,  but  unmis- 
takably gigantic.  However  modest  the  bases  of 
one's  calculation  may  be,  the  minimum  of  time 
assignable  to  the  coal  period  remains  something 
stupendous. 

Principal  Dawson  is  the  last  person  likely 
to  be  guilty  of  exaggeration  in  this  matter,  and 
it  will  be  well  to  consider  what  he  has  to  say 
about  it : — 

"  The  rate  of  accumulation  of  coal  was  very  slow.  The 
climate  of  the  period,  in  the  northern  temperate  zone,  was  of 
such  a  character  that  the  true  conifers  show  rings  of  growth, 
not  larger,  nor  much  less  distinct,  than  those  of  many  of  their 
modern  congeners.  The  Sigillarim  and  Calamites  were  not,  as 
often  supposed,  composed  wholly,  or  even  principally,  of  lax 
and  soft  tissues,  or  necessarily  short-lived.  The  former  had,  it 
is  tme,  a  very  thick  inner  bark  ;  but  their  dense  woody  axis, 
tlieir  thick  and  nearly  imperishable  outer  bark,  and  their  scanty 
and  rigid  foliage,  would  indicate  no  very  rapid  growth  or  decay. 
In  the  case  of  the  Sigillarice,  the  variations  in  the  leaf-scars  in 
different  parts  of  the  trunk,  the  intercalation  of  new  ridges  at 
the  surface  representing  that  of  new  woody  wedges  in  the  axis, 
the  transverse  marks  left  by  the  stages  of  upward  growth,  all 
indicate  that  several  years  must  have  teen  required  for  the 
growth  of  stems  of  njoderate  size.  The  enormous  roots  of  these 
trees,  and  the  condition  of  the  coal-swamps,  must  have  exemj>ted 
them  from  the  danger  of  being  overthrown  by  violence.     They 


156  ON   THE   FORMATION   OF   COAL  v 

probably  fell  in  successive  generations  from  natural  decay  ;  and 
making  every  allowance  for  other  materials,  we  may  safely  assert 
that  every  foot  of  thickness  of  pure  bituminous  coal  implies  the 
qniet  growth  and  fall  of  at  least  fifty  generations  of  Sigillarice, 
and  therefore  an  undisturbed  condition  of  forest  growth  enduring 
through  many  centuries.  Further,  there  is  evidence  that  an 
immense  amount  of  loose  parenchymatous  tissue,  and  even  of 
wood,  perished  by  decay,  and  we  do  not  know  to  what  extent 
even  the  most  durable  tissues  may  have  disappeared  in  this  way  ; 
so  that,  in  many  coal-seams,  we  may  have  only  a  very  small 
part  of  the  vegetable  matter  produced. " 

Undoubtedly  the  force  of  these  reflections  is  not 
diminished  when  the  bituminous  coal,  as  in  Britain, 
consists  of  accumulated  spores  and  spore-cases, 
rather  than  of  stems.  But,  suppose  we  adopt 
Principal  Dawson's  assumption,  that  one  foot  of 
coal  represents  fifty  generations  of  coal  plants ; 
and,  further,  make  the  moderate  supposition  that 
each  generation  of  coal  plants  took  ten  years  to 
come  to  maturity — then,  each  foot-thickness  of 
coal  represents  five  hundred  years.  The  super- 
imposed beds  of  coal  in  one  coal-field  may  amount 
to  a  thickness  of  fifty  or  sixty  feet,  and  therefore 
the  coal  alone,  in  that  field,  represents  500  X  50 
=  25,000  years.  But  the  actual  coal  is  but  an 
insignificant  portion  of  the  total  deposit,  which,  as 
has  been  seen,  may  amount  to  between  two  and 
three  miles  of  vertical  thickness.  Suppose  it  be 
12,000  feet — which  is  240  times  the  thickness  of 
the  actual  coal — is  there  any  reason  why  we  should 
believe  it  may  not  have  taken  240  times  as  long  to 
form?     I  know  of  none.     But,  in  this  case,  the 


V  ox   THE   FORMATION   OF   COAL  157 

time  which  the  coal-field  represents  would  be 
25,000  X  240  =  6,000,000  years.  As  affording  a 
definite  chronology,  of  course  such  calculations  as 
these  are  of  no  value  ;  but  they  have  much  use  in 
fixing  one's  attention  upon  a  possible  minimum. 
A  man  may  be  puzzled  if  he  is  asked  how  long 
E-ome  took  a-building ;  but  he  is  proverbially  safe 
if  he  affirms  it  not  to  have  been  built  in  a  day ; 
and  our  geological  calculations  are  all,  at  present, 
pretty  much  on  that  footing. 

A  second  consideration  which  the  study  of  the 
coal  brings  prominently  before  the  mind  of  any  one 
who  is  familiar  with  palaeontology  is,  that  the 
coal  Flora,  viewed  in  relation  to  the  enormous 
period  of  time  which  it  lasted,  and  to  the  still 
vaster  period  which  has  elapsed  since  it  flourished, 
underwent  little  change  while  it  endured,  and  in 
its  peculiar  characters,  differs  strangely  little  from 
that  which  at  present  exist. 

The  same  species  of  plants  are  to  be  met  with 
throughout  the  whole  thickness  of  a  coal-field,  and 
the  youngest  are  not  sensibly  different  from  the 
oldest.  But  more  than  this.  Notwithstanding 
that  the  carboniferous  period  is  separated  from  us 
by  more  than  the  whole  time  represented  by  the 
secondary  and  tertiary  formations,  the  great  t}^es 
of  vegetation  were  as  distinct  then  as  now.  The 
structure  of  the  modern  club-moss  furnishes  a 
complete  explanation  of  the  fossil  remains  of  the 
Zepid:de7idra,  and  the  fronds  of  some  of  the  ancient 


158  ON   THE   FORMATION   OF   COAL  v 

ferns  are  hard  to  distinguish  from  existing  ones. 
At  the  same  time,  it  must  be  remembered,  that 
there  is  nowhere  in  the  world,  at  present,  any 
forest  which  bears  more  than  a  rough  analogy  with 
a  coal-forest.  The  types  may  remain,  but  the 
details  of  their  form,  their  relative  proportions, 
their  associates,  are  all  altered.  And  the  tree-fern 
forest  of  Tasmania,  or  New  Zealand,  gives  one  only 
a  faint  and  remote  image  of  the  vegetation  of 
the  ancient  world. 

Once  more,  an  invariably-recurring  lesson  of 
geological  history,  at  whatever  point  its  study  is 
taken  up  :  the  lesson  of  the  almost  infinite  slow- 
ness of  the  modification  of  living  forms.  The 
lines  of  the  pedigrees  of  living  things  break  o^ 
almost  before  they  begin  to  converge. 

Finally,  yet  another  curious  consideration.  Let 
us  suppose  that  one  of  the  stupid,  salamander-like 
Labyrinthodonts,  which  pottered,  with  much  belly 
and  little  leg,  like  Falstaff  in  his  old  age,  among 
the  coal-forests,  could  have  had  thinking  power 
enough  in  his  small  brain  to  reflect  upon  the 
showers  of  spores  which  kept  on  falling  through 
years  and  centuries,  while  perhaps  not  one  in  ten 
million  fulfilled  its  apparent  purpose,  and  repro- 
duced the  organism  which  gave  it  birth  :  surely 
he  might  have  been  excused  for  moralizing  upon 
the  thoughtless  and  wanton  extravagance  which 
Nature  displayed  in  her  operations. 

But  we  have  the  advantage  over  our  shovel- 


V  ON  THE   FOEMATION   OF   COAL  159 

headed  predecessor — or  possibly  ancestor — and  can 
perceive  that  a  certain  vein  of  thrift  runs  through 
this  apparent  prodigahty.  Nature  is  never  in  a 
hurry,  and  seems  to  have  had  always  before  her  eyes 
the  adage,  "  Keep  a  thing  long  enough,  and  you 
will  find  a  use  for  it."  She  has  kept  her  beds  of 
coal  many  millions  of  years  without  being  able  to 
find  much  use  for  them ;  she  has  sent  them  down 
beneath  the  sea,  and  the  sea-beasts  could  make 
nothing  of  them  ;  she  has  raised  them  up  into  dry 
land,  and  laid  the  black  veins  bare,  and  still,  for 
ages  and  ages,  there  was  no  living  thing  on  the 
face  of  the  earth  that  could  see  any  sort  of  value 
in  them ;  and  it  was  only  the  other  day,  so  to 
speak,  that  she  turned  a  new  creature  out  of  her 
v^rorkshop,  who  by  degrees  acquired  sufiicient  wits 
to  make  a  fire,  and  then  to  discover  that  the  black 
rock  would  burn. 

I  suppose  that  nineteen  hundred  years  ago, 
when  Julius  Caesar  was  good  enough  to  deal  with 
Britain  as  we  have  dealt  with  New  Zealand,  the 
primaeval  Briton,  blue  with  cold  and  woad,  may 
have  known  that  the  strange  black  stone,  of 
which  he  found  lumps  here  and  there  in  his 
wanderings,  would  burn,  and  so  help  to  warm  his 
body  and  cook  his  food.  Saxon,  Dane,  and 
Norman  swarmed  into  the  land.  The  English 
people  grew  into  a  powerful  nation,  and  Nature 
still  waited  for  a  full  return  of  the  capital  she 


160  ON   THE   FORMATION   OF   COAL  v 

had  invested  in  the  ancient  club-mosses.  The 
eighteenth  century  arrived,  and  with  it  James 
Watt.  The  brain  of  that  man  was  the  spore  out  of 
which  was  developed  the  modem  steam-engine,  and 
all  the  prodigious  trees  and  branches  of  modern  in- 
dustry which  have  grown  out  of  this.  But  coal  is 
as  much  an  essential  condition  of  this  growth  and 
development  as  carbonic  acid  is  for  that  of  a  club- 
moss.  Wanting  coal,  we  could  not  have  smelted 
the  iron  needed  to  make  our  engines,  nor  have 
worked  our  engines  when  we  had  got  them.  But 
take  away  the  engines,  and  the  great  towns  of 
Yorkshire  and  Lancashire  vanish  like  a  dream. 
Manufactures  give  place  to  agTiculture  and 
pasture,  and  not  ten  men  can  live  where  now  ten 
thousand  are  amply  supported. 

Thus,  all  this  abundant  wealth  of  money  and  of 
vivid  hfe  is  Nature's  interest  upon  her  investment 
in  club-mosses,  and  the  like,  so  long  ago.  But 
what  becomes  of  the  coal  which  is  burnt  in  }aeld- 
inof  this  interest  ?  Heat  comes  out  of  it,  lio^ht 
comes  out  of  it ;  and  if  we  could  gather  together 
all  that  goes  up  the  chimney,  and  all  that  remains 
in  the  grate  of  a  thoroughly-burnt  coal-fire,  we 
should  find  ourselves  in  possession  of  a  quantity 
of  carbonic  acid,  water,  ammonia,  and  mineral 
matters,  exactly  equal  in  weight  to  the  coal.  But 
these  are  the  very  matters  with  which  Nature 
supplied  the  club-mosses  which  made   the   coal 


V  ON   THE   FORMATION   OF   COAL  161 

She  is  paid  back  principal  and  interest  at  the 
same  time ;  and  she  straightway  invests  the  car- 
bonic acid,  the  water,  and  the  ammonia  in  new 
forms  of  life,  feeding  with  them  the  plants  that 
now  live.  Thrifty  Nature  !  Surely  no  prodigal, 
but  most  notable  of  housekeepers ! 


19": 


VI 


ON  THE  BORDER  TERRITORY  BETWEEN 
THE  ANIMAL  AND  THE  VEGETABLE 
KINGDOMS 

[1876] 

In  the  whole  history  of  science  there  is  nothing 
more  remarkable  than  the  rapidity  of  the  growth 
of  biological  knowledge  within  the  last  half- 
century,  and  the  extent  of  the  modification  which 
has  thereby  been  effected  in  some  of  the  funda- 
mental conceptions  of  the  naturalist. 

In  the  second  edition  of  the  "  Regno  Animal," 
published  in  1828,  Cuvier  devotes  a  special  section 
to  the  "  Division  of  Organised  Beings  into  Animals 
and  Vegetables,"  in  w^hich  the  question  is  treated 
with  that  comprehensiveness  of  knowledge  and 
clear  critical  judgTiient  which  characterise  his 
writings,  and  justify  us  in  regarding  them  as  re- 
presentative expressions  of  the  most  extensive, 
if  not  the  profoundest,  knowledge  of  his  time. 
He    tells   us  that  living  beings  have  been  sub- 


VI  ANIMALS   AND   PLANTS  163 

divided  from  the  earliest  times  into  animated 
heings,  which  possess  sense  and  motion,  and  inani- 
mated  beings,  which  are  devoid  of  these  functions 
and  simply  vegetate. 

Although  the  roots  of  plants  direct  themselves 
towards  moisture,  and  their  leaves  towards  air  and 
light, — although  the  parts  of  some  plants  exhibit 
oscillating  movements  without  any  perceptible 
cause,  and  the  leaves  of  others  retract  when 
touched, — yet  none  of  these  movements  justify  the 
ascription  to  plants  of  perception  or  of  will.  From 
the  mobility  of  animals,  Cuvier,  with  his  charac- 
teristic partiality  for  teleological  reasoning,  de- 
duces the  necessity  of  the  existence  in  them  of  an 
alimentary  cavity,  or  reservoir  of  food,  whence 
their  nutrition  may  be  drawn  by  the  vessels,  which 
are  a  sort  of  internal  roots ;  and,  in  the  presence 
of  this  alimentary  cavity,  he  naturally  sees  the 
primary  and  the  most  important  distinction  be- 
tween animals  and  plants. 

Followinof  out  his  teleoloofical  aro^ument,  Cuvier 
remarks  that  the  organisation  of  this  cavity  and 
its  appurtenances  must  needs  vary  according  to 
the  nature  of  the  aliment,  and  the  operations 
which  it  has  to  undergo,  before  it  can  be  converted 
into  substances  fitted  for  absorption ;  while  the 
atmosphere  and  the  earth  supply  plants  with 
juices  ready  prepared,  and  which  can  be  absorbed 
immediately.  As  the  animal  body  required  to  be 
independent  of  heat  and  of  the  atmosphere,  there 


164  ANIMALS   AND   PLANTS  VI 

were  no  means  by  which  the  motion  of  its  fluids 
could  be  produced  by  internal  causes.  Hence 
arose  the  second  great  distinctive  character  of 
animals,  or  the  circulatory  system,  which  is  less 
important  than  the  digestive,  since  it  was  un- 
necessary, and  therefore  is  absent,  in  the  more 
simple  animals. 

Animals  further  needed  muscles  for  loco- 
motion and  nerves  for  sensibility.  Hence,  says 
Cuvier,  it  was  necessary  that  the  chemical  compo- 
sition of  the  animal  body  should  be  more  compli- 
cated than  that  of  the  plant ;  and  it  is  so,  inasmuch 
as  an  additional  substance,  nitrogen,  enters  into  it 
as  an  essential  element ;  while,  in  plants,  nitrogen 
is  only  accidentally  joined  with  the  three  other 
fundamental  constituents  of  organic  beings — 
carbon,  hydrogen,  and  oxygen.  Indeed,  he  after- 
wards affirms  that  nitrogen  is  peculiar  to  animals ; 
and  herein  he  places  the  third  distinction  between 
the  animal  and  the  plant.  The  soil  and  the 
atmosphere  supply  plants  with  water,  composed  of 
hydrogen  and  oxygen ;  air,  consisting  of  nitrogen 
and  oxygen  ;  and  carbonic  acid,  containing  carbon 
and  oxygen.  They  retain  the  hydrogen  and  the 
carbon,  exhale  the  superfluous  oxygen,  and  absorb 
little  or  no  nitrogen.  The  essential  character  of 
vegetable  life  is  the  exhalation  of  oxygen,  which 
is  effected  through  the  agency  of  light.  Animals, 
on  the  contrary,  derive  their  nourishment  either 
directly  or  indirectly  from  plants.     They  get  rid  of 


VI  ANIMALS  AND   PLANTS  165 

the  superfluous  liydrogen  and  carbon,  and  accumu- 
late nitrogen.  The  relations  of  plants  and 
animals  to  the  atmosphere  are  therefore  inverse. 
The  plant  withdraws  water  and  carbonic  acid  from 
the  atmosphere,  the  animal  contributes  both  to  it. 
Respiration — that  is,  the  absorption  of  oxygen  and 
the  exhalation  of  carbonic  acid — is  the  specially 
animal  function  of  animals,  and  constitutes  their 
fourth  distinctive  character. 

Thus  wi'ote  Cuvier  in  1828.  But,  in  the  fourth 
and  fifth  decades  of  this  century,  the  greatest  and 
most  rapid  revolution  which  biological  science  has 
ever  undergone  was  effected  by  the  application  of 
the  modern  microscope  to  the  investigation  of 
organic  structure;  by  the  introduction  of  exact 
and  easily  manageable  methods  of  conducting  the 
chemical  analysis  of  organic  compounds;  and 
finally,  by  the  emplo}Tiient  of  instruments  of  pre- 
cision for  the  measurement  of  the  physical  forces 
which  are  at  work  in  the  living  economy. 

That  the  semi-fluid  contents  (which  we  now 
term  protoplasm)  of  the  cells  of  certain  plants, 
such  as  the  Charm ^  are  in  constant  and  regular 
motion,  was  made  out  by  Bonaventura  Corti  a 
century  ago  ;  but  the  fact,  important  as  it  was, 
fell  into  obhvion,  and  had  to  be  rediscovered  by 
Treviranus  in  1807.  Robert  Brown  noted  the 
more  complex  motions  of  the  protoplasm  in  the 
cells  of  Tradescantia  in  1831 ;  and  now  such  move* 
ments  of  the  living  substance  of  plants  are  well 


166  ANIMALS  AND   PLANTS  vi 

known  to  be  some  of  the  most  widely-prevalent 
phenomena  of  vegetable  life. 

Agardh,  and  other  of  the  botanists  of  Cuvier's 
generation,  who  occupied  themselves  with  the 
lower  plants,  had  observed  that,  under  particular 
circumstances,  the  contents  of  the  cells  of  certain 
water-weeds  were  set  free,  and  moved  about  with 
considerable  velocity,  and  with  all  the  appearances 
of  spontaneity,  as  locomotive  bodies,  which,  from 
their  similarity  to  animals  of  simple  organisation, 
were  called  "  zoospores."  Even  as  late  as  1845, 
however,  a  botanist  of  Schleiden's  eminence  dealt 
very  sceptically  with  these  statements;  and  his 
scepticism  was  the  more  justified,  since  Ehren- 
berg,  in  his  elaborate  and  comprehensive  work  on 
the  Infusoria,  had  declared  the  greater  number  of 
what  are  now  recognised  as  locomotive  plants  to 
be  animals. 

At  the  present  day,  innumerable  plants  and  free 
plant  cells  are  known  to  pass  the  whole  or  part  of 
their  lives  in  an  actively  locomotive  condition,  in 
no  wise  distinguishable  from  that  of  one  of  the 
simpler  animals ;  and,  while  in  this  condition,  their 
movements  are,  to  all  appearance,  as  spontaneous 
— as  much  the  product  of  volition — as  those  of 
such  animals. 

Hence  the  teleological  argument  for  Cuvier's 
first  diagnostic  character — the  presence  in  animals 
of  an  alimentary  cavity,  or  internal  pocket,  in 
which  they  can  carry  about  their  nutriment — has 


n  ANIMALS   AND   PLANTS  167 

broken  down,  so  far,  at  least,  as  his  mode  of  stating 
it  goes.  And,  with  the  advance  of  microscopic 
anatomy,  the  universaHty  of  the  fact  itself  among 
animals  has  ceased  to  be  predicable.  Many 
animals  of  even  complex  structure,  which  live 
parasitically  within  others,  are  wholly  devoid  of  an 
alimentary  cavity.  Their  food  is  provided  for 
them,  not  only  ready  cooked,  but  ready  digested, 
and  the  alimentary  canal,  become  superfluous, 
has  disappeared.  Again,  the  males  of  most 
Rotifers  have  no  digestive  apparatus  ;  as  a  German 
naturalist  has  remarked,  they  devote  themselves 
entirely  to  the  "  Minnedienst,"  and  are  to  be 
reckoned  among  the  few  realisations  of  the 
Byronic  ideal  of  a  lover.  Finally,  amidst  the 
lowest  forms  of  animal  life,  the  speck  of  gelatinous 
protoplasm,  which  constitutes  the  whole  body,  has 
no  permanent  digestive  cavity  or  mouth,  but  takes 
in  its  food  anywhere ;  and  digests,  so  to  speak,  all 
over  its  body. 

But  although  Cuvier's  leading  diagnosis  of  the 
animal  from  the  plant  will  not  stand  a  strict  test, 
it  remains  one  of  the  most  constant  of  the  dis- 
tinctive characters  of  animals.  And,  if  we  sub- 
stitute for  the  possession  of  an  alimentary  cavity, 
the  power  of  taking  solid  nutriment  into  the  body 
and  there  digesting  it,  the  definition  so  changed 
will  cover  all  animals,  except  certain  parasites, 
and  the  few  and  exceptional  cases  of  non-parasitic 
animals  which  do  not  feed  at  all.     On  the  other 


168  ANIMALS   AND   PLANTS  vi 

hand,  the  definition  thus  amended  will  exclude  all 
ordinary  vegetable  organisms. 

Cuvier  himself  practically  gives  up  his  second 
distinctive  mark  when  he  admits  that  it  is  want- 
ing in  the  simpler  animals. 

The  third  distinction  is  based  on  a  completely 
erroneous  conception  of  the  chemical  differences 
and  resemblances  between  the  constituents  of 
animal  and  vegetable  organisms,  for  which  Cuvier 
is  not  responsible,  as  it  was  current  among  con- 
temporary chemists.  It  is  now  established  that 
nitrogen  is  as  essential  a  constituent  of  vegetable 
as  of  animal  hving  matter ;  and  that  the  latter  is, 
chemically  speaking,  just  as  complicated  as  the 
former.  Starchy  substances,  cellulose  and  sugar, 
once  supposed  to  be  exclusively  confined  to  plants, 
are  now  known  to  be  regular  and  normal  products 
of  animals.  Amylaceous  and  saccharine  substances 
are  largely  manufactured,  even  by  the  highest 
animals ;  cellulose  is  widespread  as  a  constituent 
of  the  skeletons  of  the  lower  animals ;  and  it  is 
probable  that  amyloid  substances  are  universally 
present  in  the  animal  organism,  though  not  in  the 
precise  form  of  starch. 

Moreover,  although  it  remains  true  that  there 
is  an  inverse  relation  between  the  green  plant  in 
sunshine  and  the  animal,  in  so  far  as,  under  these 
circumstances,  the  green  plant  decomposes  car- 
bonic acid  and  exhales  oxygen,  while  the  animal 
absorbs   oxygen   and  exhales  carbonic  acid ;  yet 


VI  ANIMALS   AND   PLANTS  169 

the  exact  researches  of  the  modern  chemical  in- 
vestigators of  the  physiological  processes  of  plants 
have  clearly  demonstrated  the  fallacy  of  attempt- 
ing to  draw  any  general  distinction  between 
animals  and  vegetables  on  this  ground.  In  fact, 
the  difference  vanishes  with  the  sunshine,  even  in 
the  case  of  the  gi^een  plant ;  which,  in  the  dark, 
absorbs  oxygen  and  gives  out  carbonic  acid  like 
any  animal.^  On  the  other  hand,  those  plants, 
such  as  the  fungi,  which  contain  no  chlorophyll 
and  are  not  green,  are  always,  so  far  as  respiration 
is  concerned,  in  the  exact  position  of  animals. 
They  absorb  oxygen  and  give  out  carbonic  acid. 

Thus,  by  the  progress  of  knowledge,  Cuvier's 
fourth  distinction  between  the  animal  and  the 
plant  has  been  as  completely  invah dated  as  the 
third  and  second ;  and  even  the  first  can  be  re- 
tained only  in  a  modified  form  and  subject  to 
exceptions. 

But  has  the  advance  of  biology  simply  tended 
to  break  down  old  distinctions,  without  establish- 
ing new  ones  ? 

With  a  qualification,  to  be  considered  presently, 
the  answer  to  this  question  is  undoubtedly  in  the 
affirmative.     The  famous  researches  of  Schwann 

1  There  is  every  reason  to  believe  that  living  plants,  like  living 
animals,  always  respire,  and.  in  respiring,  absorb  oxygen  and 
give  off  carbonic  acid  ;  but,  that  in  green  plants  exposed 
to  daylight  or  to  the  electric  light,  the  quantity  of  oxygen 
evolved  in  consequence  of  the  decomposition  of  carbonic  acid 
by  a  special  aiq)aratus  which  greeii  plants  possess  exceeds  that 
absorbed  in  the  concurrent  respiratory  process. 


170  ANIMALS   AND   PLANTS  VI 

and  Sclileiden  in  1837  and  the  following  years, 
founded  the  modern  science  of  histology,  or  that 
branch  of  anatomy  which  deals  with  the  ultimate 
visible  structure  of  organisms,  as  revealed  by  the 
microscope ;  and,  from  that  day  to  this,  the  rapid 
improvement  of  methods  of  investigation,  and  the 
energy  of  a  host  of  accurate  observers,  have  given 
greater  and  greater  breadth  and  firmness  to 
Schwann's  great  generalisation,  that  a  fundamental 
unity  of  structure  obtains  in  animals  and  plants ; 
and  that,  however  diverse  may  be  the  fabrics,  or 
tissues,  of  which  their  bodies  are  composed,  all 
these  varied  structures  result  from  the  meta- 
morphosis of  morphological  units  (termed  cells,  in 
a  more  general  sense  than  that  in  which  the  word 
"  cells  "  was  at  first  employed),  which  are  not  only 
similar  in  animals  and  in  plants  respectively,  but 
present  a  close  resemblance,  when  those  of  animals 
and  those  of  plants  are  compared  together. 

The  contractility  which  is  the  fundamental  con- 
dition of  locomotion,  has  not  only  been  discovered 
to  exist  far  more  widely  among  plants  than  was 
formerly  imagined ;  but,  in  plants,  the  act  of  con- 
traction has  been  found  to  be  accompanied,  as  Dr. 
Burdon  Sanderson's  interesting  investigations  have 
sho^vn,  by  a  disturbance  of  the  electrical  state  of 
the  contractile  substance,  comparable  to  that 
which  was  found  by  Du  Bois  Bepnond  to  be  a 
concomitant  of  the  activity  of  ordinary  muscle  in 
animals. 


TI  ANIMALS   AND  PLANTS  171 

Again,  I  know  of  no  test  by  which  the  reaction 
of  the  leaves  of  the  Sundew  and  of  other  plants  to 
stimuli,  so  fully  and  carefully  studied  by  Mr. 
Darwin,  can  be  distinguished  from  those  acts  of 
contraction  following  upon  stimuli,  which  ai'e 
called  "  reflex  "  in  animals. 

On  each  lobe  of  the  bilobed  leaf  of  Venus's  fly- 
trap {Dioncea  muscijpula)  are  three  delicate  filaments 
which  stand  out  at  right  angle  from  the  surface  of 
the  leaf  Touch  one  of  them  with  the  end  of  a 
fine  human  hair  and  the  lobes  of  the  leaf  instantly 
close  together  ^  in  virtue  of  an  act  of  contraction 
of  part  of  their  substance,  just  as  the  body  of 
a  snail  contracts  into  its  shell  when  one  of  its 
"  horns  "  is  irritated. 

The  reflex  action  of  the  snail  is  the  result  of  the 
presence  of  a  nervous  system  in  the  animal.  A 
molecular  change  takes  place  in  the  nerve  of  the 
tentacle,  is  propagated  to  the  muscles  by  which  the 
body  is  retracted,  and  causing  them  to  contract, 
the  act  of  retraction  is  brought  about.  Of  course 
the  similarity  of  the  acts  does  not  necessarily  in- 
volve the  conclusion  that  the  mechanism  by 
which  they  are  effected  is  the  same;  but  it 
suggests  a  suspicion  of  their  identity  which  needs 
careful  testing. 

The  results  of  recent  inquiries  into  the  structure 
of  the  nervous  system  of  animals  converge  towards 
the  conclusion  that  the  nerve  fibres,  which  we 
^  Darwin,  Insectivoroibs  Plants,  p.  289. 


172  ANIMALS   AND   PLANTS  vi 

have  hitherto  regarded  as  ultimate  elements  of 
nervous  tissue,  are  not  such,  but  are  simply  the 
visible  aggregations  of  vastly  more  attenuated 
filaments,  the  diameter  of  which  dwindles  down  to 
the  limits  of  our  present  microscopic  vision,  greatly 
as  these  have  been  extended  by  modern  improve- 
ments of  the  microscope ;  and  that  a  nerve  is,  in 
its  essence,  nothing  but  a  linear  tract  of  specially 
modified  protoplasm  between  two  points  of  an 
organism — one  of  which  is  able  to  affect  the  other 
by  means  of  the  communication  so  established. 
Hence,  it  is  conceivable  that  even  the  simplest 
living  being  may  possess  a  nervous  system.  And 
the  question  whether  plants  are  provided  with  a 
nervous  system  or  not,  thus  acquires  a  new  aspect, 
and  presents  the  histologist  and  physiologist  with 
a  problem  of  extreme  difficulty,  which  must  be 
attacked  jfrom  a  new  point  of  view  and  by  the  aid 
of  methods  which  have  yet  to  be  invented. 

Thus  it  must  be  admitted  that  plants  may  be 
contractile  and  locomotive ;  that,  while  locomotive, 
their  movements  may  have  as  much  appearance  of 
spontaneity  as  those  of  the  lowest  animals ;  and 
that  many  exhibit  actions,  comparable  to  those 
which  are  brought  about  by  the  agency  of  a 
nervous  system  in  animals.  And  it  must  be 
allowed  to  be  possible  that  further  research  may 
reveal  the  existence  of  something  comparable  to  a 
nervous  system  in  plants.  So  that  I  know  not 
where  we  can  hope  to  find  any  absolute  distinction 


VI  ANIMALS  AND  PLANTS  173 

between  animals  and  plants,  unless  we  return  to 
their  mode  of  nutrition,  and  inquire  whether 
certain  differences  of  a  more  occult  character  than 
those  imagined  to  exist  by  Cuvier,  and  which  cer- 
tainly hold  good  for  the  vast  majority  of  animals 
and  plants,  are  of  universal  application. 

A  bean  may  be  supplied  with  water  in  which 
salts  of  ammonia  and  certain  other  mineral  salts 
are  dissolved  in  due  proportion ;  with  atmospheric 
air  containing  its  ordinary  minute  dose  of  carbonic 
acid  ;  and  with  nothing  else  but  sunlight  and  heat. 
Under  these  circumstances,  unnatural  as  they  are, 
with  proper  management,  the  bean  will  thrust 
forth  its  radicle  and  its  plumule ;  the  former  will 
grow  down  into  roots,  the  latter  grow  up  into 
the  stem  and  leaves  of  a  vigorous  bean-plant ;  and 
this  plant  will,  in  due  time,  flower  and  produce  its 
crop  of  beans,  just  as  if  it  were  grown  in  the 
garden  or  in  the  field. 

The  weight  of  the  nitrogenous  protein  com- 
pounds, of  the  oily,  starchy,  saccharine  and  woody 
substances  contained  in  the  full-grown  plant  and  its 
seeds,  will  be  vastly  greater  than  the  weight  of  the 
same  substances  contained  in  the  bean  from  which  it 
sprang.  But  nothing  has  been  suppHed  to  the  bean 
save  water,  carbonic  acid,  ammonia,  potash,  lime, 
iron,  and  the  like,  in  combination  with  phosphoric, 
sulphuric,  and  other  acids.  Neither  protein,  nor 
fat,  nor  starch,  nor  sugar,  nor  any  substance  in  the 
slightest  degree  resembling  them,  has  formed  part 


174  ANIMALS   AND   PLANTS  VI 

of  the  food  of  the  bean.  But  the  weights  of  the 
carbon,  hydrogen,  oxygen,  nitrogen,  phosphorus, 
sulphur,  and  other  elementary  bodies  contained  in 
the  bean-plant,  and  in  the  seeds  which  it  produces, 
are  exactly  equivalent  to  the  weights  of  the  same 
elements  which  have  disappeared  from  the 
materials  supplied  to  the  bean  during  its  growth. 
Whence  it  follows  that  the  bean  has  taken  in  only 
the  raw  materials  of  its  fabric,  and  has  manu- 
factured them  into  bean-stuffs. 

The  bean  has  been  able  to  perform  this  great 
chemical  feat  by  the  help  of  its  green  colouring 
matter,  or  chlorophyll;  for  it  is  only  the  green 
parts  of  the  plant  which,  under  the  influence  of 
sunlight,  have  the  marvellous  power  of  decom- 
posing carbonic  acid,  setting  free  the  oxygen  and 
laying  hold  of  the  carbon  which  it  contains.  In 
fact,  the  bean  obtains  two  of  the  absolutely  in- 
dispensable elements  of  its  substance  from  two 
distinct  sources ;  the  watery  solution,  in  which  its 
roots  are  plunged,  contains  nitrogen  but  no  carbon  ; 
the  air,  to  which  the  leaves  are  exposed,  contains 
carbon,  but  its  nitrogen  is  in  the  state  of  a  free 
gas,  in  which  condition  the  bean  can  make  no  use 
of  it ;  ^  and  the  chlorophyll  ^  is  the  apparatus  by 

1  I  purposely  assume  that  the  air  with  which  the  bean  is 
supplied  in  the  case  stated  contains  no  aninioniacal  salts. 

-  Tlie  recent  researches  of  Pringsheim  have  raised  a  host  of 
questions  as  to  the  exact  share  taken  hy  chlorophyll  in  the 
chemical  operations  which  are  eftected  by  the  green  parts  of 
plants.  It  may  be  that  the  chlorophyll  is  only  a  constant  con- 
comitant of  the  actual  deoxidising  apparatus. 


VI 


ANIMALS   AND   PLANTS  175 


which  the  carbon  is  extracted  from  the  atmo- 
spheric carbonic  acid — the  leaves  being  the  chief 
laboratories  in  which  this  operation  is  effected. 

The  great  majority  of  conspicuous  plants  are,  as 
everybody  knows,  green ;  and  this  arises  from  the 
abundance  of  their  chlorophyll.  The  few  which 
contain  no  chlorophyll  and  are  colourless,  are  un- 
able to  extract  the  carbon  which  they  require  from 
atmospheric  carbonic  acid,  and  lead  a  parasitic 
existence  upon  other  plants ;  but  it  by  no  means 
follows,  often  as  the  statement  has  been  repeated, 
that  the  manufacturing  power  of  plants  depends 
on  their  chlorophyll,  and  its  interaction  with  the 
rays  of  the  sun.  On  the  contrary,  it  is  easily 
demonstrated,  as  Pasteur  first  proved,  that  the 
lowest  fungi,  devoid  of  chlorophyll,  or  of  any  sub- 
stitute for  it,  as  they  are,  nevertheless  possess  the 
characteristic  manufacturing  powers  of  plants  in  a 
very  high  degree.  Only  it  is  necessary  that  they 
should  be  supplied  with  a  different  kind  of  raw 
material ;  as  they  cannot  extract  carbon  from  car- 
bonic acid,  they  must  be  furnished  with  something 
else  that  contains  carbon.  Tartaric  acid  is  such  a 
substance ;  and  if  a  single  spore  of  the  commonest 
and  most  troublesome  of  moulds — Penicillium — be 
sown  in  a  saucerful  of  water,  in  which  tartrate  of 
ammonia,  with  a  small  percentage  of  phosphates 
and  sulphates  is  contained,  and  kept  warm,  whether 
in  the  dark  or  exposed  to  light,  it  will,  in  a 
short  time,  give  rise  to  a  thick  crust  of  mould, 


176  ANIMALS  AND   PLANTS  vi 

which  contains  many  million  times  the  weight  of 
the  original  spore,  in  protein  compounds  and 
cellulose.  Thus  we  have  a  very  wide  basis  of  fact 
for  the  generalisation  that  plants  are  essentially 
characterised  by  their  manufacturing  capacity — by 
their  power  of  working  up  mere  mineral  matters 
into  complex  organic  compounds. 

Contrariwise,  there  is  a  no  less  wide  foundation 
for  the  generalisation  that  animals,  as  Cuvier  puts 
it,  depend  directly  or  indirectly  upon  plants  for 
the  materials  of  their  bodies ;  that  is,  either  they 
are  herbivorous,  or  they  eat  other  animals  which 
are  herbivorous. 

But  for  what  constituents  of  their  bodies  are 
animals  thus  dependent  upon  plants  ?  Certainly 
not  for  their  horny  matter ;  nor  for  chondrin,  the 
proximate  chemical  element  of  cartilage  ;  nor  for 
gelatine ;  nor  for  syntonin,  the  constituent  of 
muscle;  nor  for  their  nervous  or  biliary  sub- 
stances; nor  for  their  amyloid  matters;  nor, 
necessarily,  for  their  fats. 

It  can  be  experimentally  demonstrated  that 
animals  can  make  these  for  themselves.  But  that 
which  they  cannot  make,  but  must,  in  all  known 
cases,  obtain  directly  or  indirectly  from  plants,  is 
the  peculiar  nitrogenous  matter,  protein.  Thus 
the  plant  is  the  ideal  proUtaire  of  the  living 
world,  the  worker  who  produces ;  the  animal,  the 
ideal  aristocrat,  who  mostly  occupies  himself  in 
consuming,  after  the  manner  of  that  noble  repre- 


VI  ANIMALS   AND   PLANTS  177 

sentative  of  the  line  of  Zahdarm,  whose  epitaph  is 
written  in  "  Sartor  Resartus." 

Here  is  our  last  hope  of  finding  a  sharp  line  of 
demarcation  between  plants  and  animals;  for,  as 
I  have  already  hinted,  there  is  a  border  territory 
between  the  two  kingdoms,  a  sort  of  no-man's- 
land,  the  inhabitants  of  which  certainly  cannot 
be  discriminated  and  brought  to  their  proper 
allegiance  in  any  other  way. 

Some  months  ago.  Professor  Tyndall  asked  me 
to  examine  a  drop  of  infusion  of  hay,  placed 
under  an  excellent  and  powerful  microscope,  and 
to  tell  him  what  I  thought  some  organisms 
visible  in  it  were.  I  looked  and  observed,  in  the 
first  place,  multitudes  of  Bacteria  moving  about 
with  their  ordinary  intermittent  spasmodic 
wriggles.  As  to  the  vegetable  nature  of  these 
there  is  now  no  doubt.  Not  only  does  the  close 
resemblance  of  the  Bacteria  to  unquestionable 
plants,  such  as  the  Oscillatorice  and  the  lower  forms 
of  Ficngi,  justify  this  conclusion,  but  the  manu- 
facturing test  settles  the  question  at  once.  It 
is  only  needful  to  add  a  minute  drop  of  fluid 
containing  Bacteria,  to  water  in  which  tartrate, 
phosphate,  and  sulphate  of  ammonia  are  dissolved ; 
and,  in  a  very  short  space  of  time,  the  clear  fluid 
becomes  milky  by  reason  of  their  prodigious 
multiplication,  which,  of  course,  implies  the 
manufacture  of  living  Bacterium-stufif  out  of 
these  merely  saline  matters, 

198 


178  ANIMALS   AND   PLANTS  vi 

But  other  active  organisms,  very  much  larger 
than  the  Bacteria^  attaining  in  fact  the  com- 
paratively gigantic  dimensions  of  -g-oVo  ^^  ^^ 
inch  or  more,  incessantly  crossed  the  field  of  view. 
Each  of  these  had  a  body  shaped  like  a  pear,  the 
small  end  being  slightly  incurved  and  produced 
into  a  long  curved  filament,  or  cilmm,  of  extreme 
tenuity.  Behind  this,  from  the  concave  side  of 
the  incurvation,  proceeded  another  long  cilium, 
so  delicate  as  to  be  discernible  only  by  the  use  of 
the  highest  powers  and  careful  management  of 
the  light.  In  the  centre  of  the  pear-shaped 
body  a  clear  round  space  could  occasionally  be 
discerned,  but  not  always;  and  careful  watching 
showed  that  this  clear  vacuity  appeared  gradually, 
and  then  shut  up  and  disappeared  suddenly,  at 
regular  intervals.  Such  a  structure  is  of  common 
occurrence  among  the  lowest  plants  and  animals, 
and  is  known  as  a  contractile  vacuole. 

The  little  creature  thus  described  sometimes 
propelled  itself  with  great  activity,  with  a  curious 
rolling  motion,  by  the  lashing  of  the  front  cilium, 
while  the  second  cilium  trailed  behind;  some- 
times it  anchored  itself  by  the  hinder  cilium  and 
was  spun  round  by  the  working  of  the  other,  its 
motions  resembling  those  of  an  anchor  buoy  in  a 
heavy  sea.  Sometimes,  when  two  were  in  full 
career  towards  one  another,  each  would  appear 
dexterously  to  get  out  of  the  other's  way ;  some- 
times  a  crowd   would   assemble  and   jostle    one 


VI  ANIMALS   AND   PLANTS  179 

anotlier,  with  as  much  semblance  of  individual 
effort  as  a  spectator  on  the  Grands  Mulets  might 
observe  with  a  telescope  among  the  specks  repre- 
senting men  in  the  valley  of  Chamounix. 

The  spectacle,  though  always  surprising,  was 
not  new  to  me.  So  my  reply  to  the  question  put 
to  me  was,  that  these  organisms  were  what 
biologists  call  Monads,  and  though  they  might  be 
animals,  it  was  also  possible  that  they  might, 
like  the  Bacteria,  be  plants.  My  friend  received 
my  verdict  with  an  expression  which  showed  a 
sad  want  of  respect  for  authority.  He  would  as 
soon  believe  that  a  sheep  was  a  plant.  Naturally 
piqued  by  this  want  of  faith,  I  have  thought  a 
good  deal  over  the  matter ;  and,  as  I  still  rest  in 
the  lame  conclusion  I  originally  expressed,  and 
must  even  now  confess  that  I  cannot  certainly 
say  whether  this  creature  is  an  animal  or  a  plant, 
I  think  it  may  be  well  to  state  the  grounds  of  my 
hesitation  at  length.  But,  in  the  first  place,  in 
order  that  I  may  conveniently  distinguish  this 
"  Monad "  from  the  multitude  of  other  things 
which  go  by  the  same  designation,  I  must  give  it 
a  name  of  its  own.  I  think  (though,  for  reasons 
which  need  not  be  stated  at  present,  I  am  not 
quite  sure)  that  it  is  identical  with  the  species 
Mooias  lens,  as  defined  by  the  eminent  French 
microscopist  Dujardin,  though  his  magnifying 
power  was  probably  insufficient  to  enable  him 
to  see  that  it   is  curiously  like    a  much    larger 


180  ANIMALS   AND   PLANTS  vi 

form  of  monad  whicli  lie  has  named  Hcteromita. 
I  shall,  therefore,  call  it  not  Monas,  but  Hetcrcmita 
lens. 

I  have  been  unable  to  devote  to  my  Heteromita 
the  prolonged  study  needful  to  work  out  its  whole 
history,  which  would  involve  weeks,  or  it  may  be 
months,  of  unremitting  attention.  But  I  the  less 
regret  this  circumstance,  as  some  remarkable 
observations  recently  published  by  Messrs.  Dal- 
linger  and  Drysdale  ^  on  certain  Monads,  relate, 
in  part,  to  a  form  so  similar  to  my  Hdcrcmita 
lens,  that  the  history  of  the  one  may  be  used  to 
illustrate  that  of  the  other.  These  most  patient 
and  painstaking  observers,  who  employed  the 
highest  attainable  powers  "of  the  microscope  and, 
relieving  one  another,  kept  watch  day  and  night 
over  the  same  individual  monads,  have  been 
enabled  to  trace  out  the  whole  history  of  their 
Heteromita  ;  which  they  found  in  infusions  of  the 
heads  of  fishes  of  the  Cod  tribe. 

Of  the  four  monads  described  and  figured  by 
these  investigators,  one,  as  I  have  said,  very 
closely  resembles  Heteromita  lens  in  every 
particular,  except  that  it  has  a  separately  dis- 
tinguishable central  particle  or  "  nucleus,"  which 
is  not  certainly  to  be  made  out  in  Heteromita 
lens ;  and  that  nothing  is  said  by  Messrs.  DaUinger 

^  *'  Researclies  in  the  Life  history  of  a  Cercomonad  :  a  Lesson 
In  Biogenesis";  and  "Furtlier  Ecsearches  in  the  Life-histoi7 
of  the  Monads." — Monthly  Micruscopkal  Journal,  1S73. 


VI  ANIMALS  AND   PLANTS  181 

and  Diysdale  of  the  existence  of  a  contractile 
vacuole  in  this  monad,  though  they  describe  it  in 
another. 

Their  Heteromita,  however,  multiplied  rapidly 
by  fission.  Sometimes  a  transverse  constriction 
appeared ;  the  hinder  half  developed  a  new  cilium, 
and  the  hinder  cilium  gradually  split  from  its 
base  to  its  free  end,  until  it  was  divided  into 
two  ;  a  process  which,  considering  the  fact  that 
this  fine  filament  cannot  be  much  more  than 
To  0^0  0  0  ^f  ^^  'vcioh.  in  diameter,  is  wonderful 
enough.  The  constriction  of  the  body  extended 
inwards  until  the  two  portions  were  united  by  a 
narrow  isthmus ;  finally,  they  separated  and  each 
swam  away  by  itself,  a  complete  Heteromita, 
provided  with  its  two  cilia.  Sometimes  the  con- 
striction took  a  longitudinal  direction,  with  the 
same  ultimate  result.  In  each  case  the  process 
occupied  not  more  than  six  or  seven  minutes. 
At  this  rate,  a  single  Heteromita  would  give  rise 
to  a  thousand  like  itself  in  the  course  of  an  hour, 
to  about  a  million  in  two  hours,  and  to  a  number 
greater  than  the  generally  assumed  number  of 
human  beings  now  living  in  the  world  in  three 
hours ;  or,  if  we  give  each  Heteromita  an  hour's 
enjoyment  of  individual  existence,  the  same  result 
will  be  obtained  in  about  a  day.  The  apparent 
suddenness  of  the  appearance  of  multitudes  of 
such  organisms  as  these,  in  any  nutritive  fluid  to 
which  one  obtains  access,  is  thus  easily  explained. 


182  ANIMALS   AND   PLANTS 


VI 


'  During  these  processes  of  multiplication  by- 
fission,  the  Heteromita,  remains  active ;  but  some- 
times another  mode  of  fission  occurs.  The  body 
becomes  rounded  and  quiescent,  or  nearly  so ;  and, 
while  in  this  resting  state,  divides  into  two 
portions,  each  of  which  is  rapidly  converted  into 
an  active  Hctercmita. 

A  still  more  remarkable  phenomenon  is  that 
kind  of  multiplication  which  is  preceded  by  the 
union  of  two  monads,  by  a  process  which  is  termed 
conjugation.  Two  active  Hetcromitce  become  applied 
to  one  another,  and  then  slowly  and  gradually  coa- 
lesce into  one  body.  The  two  nuclei  run  into  one ; 
and  the  mass  resulting  from  the  conjugation  of  the 
two  Heteromitm,  thus  fused  together,  has  a  tri- 
angular form.  The  two  pairs  of  cilia  are  to  be 
seen,  for  some  time,  at  two  of  the  angles,  which 
answer  to  the  small  ends  of  the  conjoined  monads ; 
but  they  ultimately  vanish,  and  the  twin  organ- 
ism, in  which  all  visible  traces  of  organisation 
have  disappeared,  falls  into  a  state  of  rest. 
Sudden  wave-like  movements  of  its  substance 
next  occur;  and,  in  a  short  time,  the  apices  of 
the  triangular  mass  burst,  and  give  exit  to  a 
dense  yellowish,  glairy  fluid,  filled  with  minute 
granules.  This  process,  which,  it  will  be  observed, 
involves  the  actual  confluence  and  mixture  of  the 
substance  of  two  distinct  organisms,  is  effected  in 
the  space  of  about  two  hours. 

The   authors  whom    I    quote    say  that    they 


VI 


ANIMALS  AND   PLANTS  183 


"  cannot  express  "  tlie  excessive  minuteness  of  ttie 
granules  in  question,  and  they  estimate  their 
diameter  at  less  than  o-owo  "o  ^f  ^^  inch.  Under 
the  highest  powers  of  the  microscope,  at  present 
apphcable,  such  specks  are  hardly  discernible. 
Nevertheless,  particles  of  this  size  are  massive 
when  compared  to  physical  molecules;  whence 
there  is  no  reason  to  doubt  that  each,  small  as  it 
is,  may  have  a  molecular  structure  sufficiently 
complex  to  give  rise  to  the  phenomena  of  life. 
And,  as  a  matter  of  fact,  by  patient  watching  of 
the  place  at  which  these  infinitesimal  living 
particles  were  discharged,  our  observers  assured 
themselves  of  their  growth  and  development  into 
new  monads.  In  about  four  hours  from  their 
being  set  free,  they  had  attained  a  sixth  of  the 
length  of  the  parent,  with  the  characteristic  ciHa, 
though  at  first  they  were  quite  motionless ;  and, 
in  four  hours  more,  they  had  attained  the  dimen- 
sions and  exhibited  all  the  activity  of  the  adult. 
These  inconceivably  minute  particles  are  therefore 
the  germs  of  the  Hetercmita ;  and  from  the 
dimensions  of  these  germs  it  is  easily  shown  that 
the  body  formed  by  conjugation  may,  at  a  low 
estimate,  have  given  exit  to  thirty  thousand  of 
them ;  a  result  of  a  matrimonial  process  whereby 
the  contracting  parties,  without  a  metaphor,  "  be- 
come one  flesh,"  enough  to  make  a  Malthusian 
despair  of  the  future  of  the  Universe. 

I   am   not  aware  that  the  investigators  firora 


184  ANIMALS   AND   PLANTS  vi 

whom  I  have  borrowed  this  history  have  en- 
deavoured to  ascertain  whether  their  monads  take 
sohd  nutriment  or  not ;  so  that  though  they  help 
•QS  very  much  to  fill  up  the  blanks  in  the  history 
of  my  Heteromita,  their  observations  throw  no 
light  on  the  problem  we  are  trying  to  solve — Is  it 
an  animal  or  is  it  a  plant  ? 

Undoubtedly  it  is  possible  to  bring  forward 
very  strong  arguments  in  favour  of  regarding 
Heteromita  as  a  plant. 

For  example,  there  is  a  Fungus,  an  obscure  and 
almost  microscopic  mould,  termed  Peroncspcra 
infestans.  Like  many  other  Fungi,  the  Perono- 
sporce  are  parasitic  upon  other  plants;  and  this 
particular  Peronospora  happens  to  have  attained 
much  notoriety  and  pohtical  importance,  in  a  way 
not  without  a  parallel  in  the  career  of  notorious 
politicians,  namely,  by  reason  of  the  frightful 
mischief  it  has  done  to  mankind.  For  it  is  this 
Fungus  which  is  the  cause  of  the  potato  disease ; 
and,  therefore,  Peronospora  infestans  (doubtless  of 
exclusively  Saxon  origin,  though  not  accurately 
known  no  be  so)  brought  about  the  Irish  famine. 
The  plants  afflicted  with  the  malady  are  found  to 
be  infested  by  a  mould,  consisting  of  fine  tubular 
filaments,  termed  hyphce,  which  burrow  through 
the  substance  of  the  potato  plant,  and  appropriate 
to  themselves  the  subs^n^i^e  of  their  host;  while, 
at  the  same  time,  directly  or  indirectly,  they  set 
up   chemical  changes  by  which  even  its  woody 


VI  ANIMALS   AND   PLANTS  185 

framework     becomes     blackened,     sodden,     and 
withered. 

In  structure,  however,  the  Peronosiwra  is  as 
much  a  mould  as  the  common  Penicillium ;  and 
just  as  the  Penicillium  multiplies  by  the  breaking 
up  of  its  hj^hge  into  separate  rounded  bodies,  the 
spores;  so,  in  the  Peronospora,  certain  of  the 
hyphse  grow  out  into  the  air  through  the  interstices 
of  the  superficial  cells  of  the  potato  plant,  and 
develop  spores.  Each  of  these  hj^phse  usually 
gives  off  several  branches.  The  ends  of  the 
branches  dilate  and  become  closed  sacs,  which 
eventually  drop  off  as  spores.  The  spores  falling 
on  some  part  of  the  same  potato  plant,  or  carried 
by  the  wind  to  another,  may  at  once  germinate, 
throAving  out  tubular  prolongations  which  become 
h}^h8e,  and  burrow  into  the  substance  of  the 
plant  attacked.  But,  more  commonly,  the  con- 
tents of  the  spore  divide  into  six  or  eight  separate 
portions.  The  coat  of  the  spore  gives  way,  and 
each  portion  then  emerges  as  an  independent 
organism,  which  has  the  shape  of  a  bean,  rather 
narrower  at  one  end  than  the  other,  convex  on  one 
side,  and  depressed  or  concave  on  the  opposite. 
From  the  depression,  two  long  and  delicate  ciha 
proceed,  one  shorter  than  the  other,  and  directed 
forwards.  Close  to  the  origin  of  these  cilia,  in  the 
substance  of  the  body,  is  a  regularly  pulsating, 
contractile  vacuole.  The  shorter  cihum  vibrates 
actively,  and  effects  the  locomotion  of  the  organ- 


186  ANIMALS   AND   PLANTS  vi 

ism,  while  the  other  trails  behind;  the  whole 
body  rolling  on  its  axis  with  its  pointed  end 
forwards. 

The  eminent  botanist,  De  Bary,  who  was  not 
thinking  of  our  problem,  tells  us,  in  describing  the 
movements  of  these  "Zoospores,"  that,  as  they 
swim  about,  "  Foreign  bodies  are  carefully  avoided, 
and  the  whole  movement  has  a  deceptive  likeness 
to  the  voluntary  changes  of  place  which  are 
observed  in  microscopic  animals." 

After  swarming  about  in  this  way  in  the 
moisture  on  the  surface  of  a  leaf  or  stem  (which, 
film  though  it  may  be,  is  an  ocean  to  such  a  fish) 
for  half  an  hour,  more  or  less,  the  movement  of 
the  zoospore  becomes  slower,  and  is  limited  to  a 
slow  turning  upon  its  axis,  without  change  of 
place.  It  then  becomes  quite  quiet,  the  ciha  dis- 
appear, it  assumes  a  spherical  form,  and  surrounds 
itself  with  a  distinct,  though  dehcate,  membranous 
coat.  A  protuberance  then  grows  out  from  one 
side  of  the  sphere,  and  rapidly  increasing  in  length, 
assumes  the  character  of  a  hy]Dha.  The  latter 
penetrates  into  the  substance  of  the  potato  plant, 
either  by  entering  a  stomate,  or  by  boring  through 
the  wall  of  an  epidermic  cell,  and  ramifies,  as  a 
mycelium,  in  the  substance  of  the  plant,  destroying 
the  tissues  with  which  it  comes  in  contact.  As 
these  processes  of  multiplication  take  place  very 
rapidly,  millions  of  spores  are  soon  set  free  from  a 
single  infested  plant ;  and,  from  their  minuteness, 


VI 


ANIMALS   AND   PLANTS  187 


they  are  readily  transported  by  the  gentlest 
breeze.  Since,  again,  the  zoospores  set  free  from 
each  spore,  in  virtue  of  their  powers  of  locomotion, 
swiftly  disperse  themselves  over  the  surface,  it  is 
no  wonder  that  the  infection,  once  started,  soon 
spreads  from  field  to  field,  and  extends  its  ravages 
over  a  whole  country. 

However,  it  does  not  enter  into  my  present 
plan  to  treat  of  the  potato  disease,  instructively  as 
its  history  bears  upon  that  of  other  epidemics ; 
and  I  have  selected  the  case  of  the  Peroncsi^orcb 
simply  because  it  affords  an  example  of  an  organ- 
ism, which,  in  one  stage  of  its  existence,  is  truly  a 
"  Monad,"  indistinguishable  by  any  important 
character  from  our  Hderomita,  and  extraordinarily 
like  it  in  some  respects.  And  yet  this  "  Monad  " 
can  be  traced,  step  by  step,  through  the  series  of 
metamorphoses  which  I  have  described,  until  it 
assumes  the  features  of  an  organism,  which  is  as 
much  a  plant  as  is  an  oak  or  an  elm. 

Moreover,  it  would  be  possible  to  pursue  the 
analogy  farther.  Under  certain  circumstances,  a 
process  of  conjugation  takes  place  in  the  Ferono- 
spora.  Two  separate  portions  of  its  protoplasm 
become  fused  together,  surround  themselves  with 
a  thick  coat,  and  give  rise  to  a  sort  of  vegetable 
Qgg  called  an  oospore.  After  a  period  of  rest,  the 
contents  of  the  oospore  break  up  into  a  number  of 
zoospores  like  those  already  described,  each  of 
which,  after  a  period  of  activity,  germinates  in  the 


188  ANIMALS   AND   PLANTS  VI 

ordinary  way.  This  process  obviously  corresponds 
with  the  conjugation  and  subsequent  setting  free 
of  germs  in  the  Heteromita. 

But  it  may  be  said  that  the  Peronospora  is, 
after  all,  a  questionable  sort  of  plant ;  that  it  seems 
to  be  wanting  in  the  manufacturing  power,  selected 
as  the  main  distinctive  character  of  vegetable 
life ;  or,  at  any  rate,  that  there  is  no  proof  that 
it  does  not  get  its  protein  matter  ready  made 
from  the  potato  plant. 

Let  us,  therefore,  take  a  case  which  is  not  open 
to  these  objections. 

There  are  some  small  plants  known  to  botanists 
as  members  of  the  genus  Coleochccte,  which,  with- 
out being  truly  parasitic,  grow  upon  certain 
water-weeds,  as  lichens  grow  upon  trees.  The 
little  plant  has  the  form  of  an  elegant  green  star, 
the  branching  arms  of  which  are  divided  into 
cells.  Its  greenness  is  due  to  its  chlorophyll,  and 
it  undoubtedly  has  the  manufacturing  power  in 
full  degree,  decomposing  carbonic  acid  and  setting 
oxygen  free,  under  the  influence  of  sunlight.  But 
the  protoplasmic  contents  of  some  of  the  cells  of 
which  the  plant  is  made  up  occasionally  divide,  by 
a  method  similar  to  that  which  effects  the  division 
of  the  contents  of  the  Peronospora  spore ;  and  the 
severed  portions  are  then  set  free  as  active  monad - 
like  zoospores.  Each  is  oval  and  is  provided  at 
one  extremity  with  two  long  active  ciHa.  Pro- 
pelled by  these,  it  swims  about  for  a  longer  or 


VI  ANIMALS   AND   PLANTS  189 

shorter  time,  but  at  length  comes  to  a  state  of 
rest  and  gradually  grows  into  a  Coleochcete. 
Moreover,  as  in  the  Peroiiospora,  conjugation  may 
take  place  and  result  in  an  oospore ;  the  contents 
of  which  divide  and  are  set  free  as  monadiform 
germs. 

If  the  whole  history  of  the  zoospores  of  Perono- 
spora  and  of  Goleochcete  were  unknown,  they  would 
undoubtedly  be  classed  among  "  Monads "  with 
the  same  right  as  Hcteromita  ;  why  then  may  not 
Heteromita  be  a  plant,  even  though  the  cycle  of 
forms  through  which  it  passes  shows  no  terms 
quite  so  complex  as  those  which  occur  in  Perono- 
spora  and  Coleoclimte  .^  And,  in  fact,  there  are 
some  green  organisms,  in  every  respect  charac- 
teristically plants,  such  as  Chlamydomonas, 
and  the  common  Volvox,  or  so-called  "  Globe 
animalcule,"  which  run  through  a  cycle  of  forms 
of  just  the  same  simple  character  as  those  of 
Heteromita. 

The  name  of  CMamyclomonas  is  applied  to  certain 
microscopic  green  bodies,  each  of  which  consists  of 
a  protoplasmic  central  substance  invested  by  a 
structureless  sac.  The  latter  contains  cellulose,  as 
in  ordinary  plants;  and  the  chlorophyll  which 
gives  the  green  colour  enables  the  Chlamydomonas 
to  decompose  carbonic  acid  and  fix  carbon  as  they 
do.  Two  long  cilia  protrude  through  the  cell-wall, 
and  effect  the  rapid  locomotion  of  this  "  monad," 
which,   in   all   respects   except    its    mobility,    is 


190  ANIMALS   AND   PLANTS  VI 

characteristically  a  plant.  Under  ordinary  cir- 
cumstances, the  Chlainydomonas  multiplies  by 
simple  fission,  each  splitting  into  two  or  into  four 
parts,  which  separate  and  become  independent 
organisms.  Sometimes,  however,  the  Clilamy- 
domonas  divides  into  eight  parts,  each  of  which  is 
provided  with  four  instead  of  two  cilia.  These 
"zoospores"  conjugate  in  pairs,  and  give  rise  to 
quiescent  bodies,  which  multiply  by  division,  and 
eventually  pass  into  the  active  state. 

Thus,  so  far  as  outward  form  and  the  general 
character  of  the  cycle  of  modifications,  through 
which  the  organism  passes  in  the  course  of  its 
life,  are  concerned,  the  resemblance  between 
Chlamy domonas  and  HeUromita  is  of  the  closest 
description.  And  on  the  face  of  the  matter  there 
is  no  ground  for  refusing  to  admit  that  Heteromita 
may  be  related  to  Chlamy  domonas,  as  the  colourless 
fungus  is  to  the  green  alga.  Volvox  may  be  com- 
pared to  a  hollow  sphere,  the  wall  of  which  is 
made  up  of  coherent  Chlamydomonads  ;  and  which 
progresses  with  a  rotating  motion  effected  by  the 
paddling  of  the  multitudinous  pairs  of  cilia  which 
project  from  its  surface.  Each  Volvox-m.ona,d, 
moreover,  possesses  a  red  pigment  spot,  like  the 
simplest  form  of  eye  known  among  animals.  The 
methods  of  fissive  multiplication  and  of  conjugation 
observed  in  the  monads  of  this  locomotive  globe 
are  essentially  similar  to  those  observed  in  Chlamy- 
domonas;    and,  though  a  hard   battle   has   been 


VT  ANIMALS    AND    PLANTS  191 

fought  over  it,  Volvox  is  now  finally  surrendered  to 
the  Botanists. 

Thus  there  is  really  no  reason  why  Hderonnita 
may  not  be  a  plant;  and  this  conclusion  would  be 
very  satisfactory,  if  it  were  not  equally  easy  to 
show  that  there  is  really  no  reason  why  it  should 
not  be  an  animal.  For  there  are  numerous 
organisms  presenting  the  closest  resemblance  to 
Heteromita,  and,  like  it,  grouped  under  the  general 
name  of  "  Monads,"  which,  nevertheless,  can  be 
observed  to  take  in  solid  nutriment,  and  which, 
therefore,  have  a  virtual,  if  not  an  actual,  mouth 
and  digestive  cavity,  and  thus  come  under  Cuvier's 
definition  of  an  animal.  Numerous  forms  of  such 
animals  have  been  described  by  Ehrenberg, 
Dujardin,  H.  James  Clark,  and  other  writers  on 
the  Infusoria.  Indeed,  in  another  infusion 
of  hay  in  which  my  Heteromita  lens  occurred, 
there  were  innumerable  such  infusorial  animalcules 
belonging  to  the  well-known  species  Colpcda 
cucullus} 

Full-sized  specimens  of  this  animalcule  attain  a 
length  of  between  -g-J-g-  or  -^^^  of  an  inch,  so  that  it 
may  have  ten  times  the  length  and  a  thousand 
times  the  mass  of  a  Heteromita.  In  shape,  it  is 
not  altogether  unlike  Heteromita,  The  small  end, 
however,  is  not  produced  into  one  long  cilium, 
but  the  general  surface  of  the  body  is  covered  with 

*  Excellently  described  by  Stein,  almost  all  of  whose  state- 
ments I  have  verified. 


192  ANIMALS   AND    PLANTS  vi 

small  actively  vibrating  ciliary  organs,  which  are 
only  longest  at  the  small  end.  At  the  point 
which  answers  to  that  from  which  the  two  cilia 
arise  in  Heteromita,  there  is  a  conical  depression, 
the  mouth ;  and,  in  young  specimens,  a  tapering 
filament,  which  reminds  one  of  the  posterior  cilium 
of  Heteromita,  projects  from  this  region. 

The  body  consists  of  a  soft  granular  proto- 
plasmic substance,  the  middle  of  which  is  occupied 
by  a  large  oval  mass  called  the  "  nucleus  " ;  while, 
at  its  hinder  end,  is  a  "  contractile  vacuole,"  con- 
spicuous by  its  regular  rh}iihmic  appearances  and 
disappearances.  Obviously,  although  the  Colpoda 
is  not  a  monad,  it  differs  from  one  only  in  subor- 
dinate details.  Moreover,  under  certain  conditions, 
it  becomes  quiescent,  incloses  itself  in  a  delicate 
case  or  cyst,  and  then  divides  into  two,  four,  or 
more  portions,  which  are  eventually  set  free  and 
swim  about  as  active  Colpodce. 

But  this  creature  is  an  unmistakable  animal, 
and  full-sized  Col])odce  may  be  fed  as  easily  as  one 
feeds  chickens.  It  is  only  needful  to  diffuse  very 
finely  ground  carmine  through  the  water  in  which 
they  hve,  and,  in  a  very  short  time,  the  bodies  of 
the  Colpcdce  are  stuffed  mth  the  deeply-coloured 
granules  of  the  pigment. 

And  if  this  were  not  sufficient  evidence  of  the 
animahty  of  Colpoda,  there  comes  the  fact  that  it 
is  even  more  similar  to  another  well-knowm 
animalcule,  Paramcecium;  than  it  is  to  a  monad. 


n  ANIMALS   AND   PLANTS  193 

But  Paramcecium  is  so  huge  a  creature  compared 
with  those  hitherto  discussed — it  reaches  y^-g-  of 
an  inch  or  more  in  length — that  there  is  no  diffi- 
culty in  making  out  its  organisation  in  detail; 
and  in  proving  that  it  is  not  only  an  animal,  but 
that  it  is  an  animal  which  possesses  a  somewhat 
compHcated  organisation.  For  example,  the  sur- 
face layer  of  its  body  is  different  in  structure  from 
the  deeper  parts.  There  are  two  contractile 
vacuoles,  from  each  of  which  radiates  a  system  of 
vessel-hke  canals ;  and  not  only  is  there  a  conical 
depression  continuous  with  a  tube,  which  serve  as 
mouth  and  gullet,  but  the  food  ingested  takes  a 
definite  course,  and  refuse  is  rejected  from  a 
definite  region.  Nothing  is  easier  than  to  feed 
these  animals,  and  to  watch  the  particles  of  indigo 
or  carmine  accumulate  at  the  lower  end  of  the 
gullet.  From  this  they  gradually  project,  sur- 
rounded by  a  ball  of  water,  which  at  length  passes 
with  a  jerk,  oddly  simulating  a  gulp,  into  the 
pulpy  central  substance  of  the  body,  there  to  cir- 
culate up  one  side  and  down  the  other,  until  its 
contents  are  digested  and  assimilated.  Neverthe- 
less, this  complex  animal  multiplies  by  division,  as 
the  monad  does,  and,  like  the  monad,  undergoes 
conjugation.  It  stands  in  the  same  relation  to 
Heteromita  on  the  animal  side,  as  ColeccJicete  does 
on  the  plant  side.  Start  from  either,  and  such  an 
insensible  series  of  gradations  leads  to  the  monad 
that  it  is  impossible  to  say  at  any  stage  of  the 

199 


194  ANIMALS   AND    PLAXTS 


VI 


progress  where  the  line  between  the  animal  and 
the  plant  must  be  drawn. 

There  is  reason  to  think  that  certain  organisms 
which  pass  through  a  monad  stage  of  existence, 
such  as  the  Myxomycetcs,  are,  at  one  time  of  their 
lives,  dependent  upon  external  sources  for  their 
protein  matter,  or  are  animals;  and,  at  another 
period,  manufacture  it,  or  are  plants.  And  seeing 
that  the  whole  progress  of  modern  investigation  is 
in  favour  of  the  doctrine  of  continuit}^,  it  is  a  fair 
and  probable  speculation — though  only  a  specu- 
lation— that,  as  there  are  some  plants  which  can 
manufacture  protein  out  of  such  apparently  in- 
tractable mineral  matters  as  carbonic  acid,  water, 
nitrate  of  ammonia,  metaUic  and  earthy  salts ;  while 
others  need  to  be  supplied  with  their  carbon  and 
nitrogen  in  the  somewhat  less  raw  form  of  tartrate 
of  ammonia  and  allied  compounds ;  so  there  may  be 
yet  others,  as  is  possibly  the  case  with  the  true 
parasitic  plants,  which  can  only  manage  to  put 
together  materials  still  better  prepared — still  more 
nearly  approximated  to  protein — until  we  arrive  at 
such  organisms  as  the  Psorospermice  and  the  Pan- 
Msto2ohyton,  which  are  as  much  animal  as  vegetable 
in  structure,  but  are  animal  in  their  dependence 
on  other  organisms  for  their  food. 

The  singular  circumstance  observed  by  Meyer, 
that  the  Tomtla  of  yeast,  though  an  indubitable 
plant,  still  flourishes  most  vigorously  when  supplied 
with  the  complex  nitrogenous  substance,  pepsin ; 


VI  ANIMALS   AND   PLANTS  195 

the  probability  that  the  PeronosiJora  is  nourished 
directly  by  the  protoplasm  of  the  potato-plant; 
and  the  wonderful  facts  which  have  recently  been 
brought  to  Hght  respecting  insectivorous  plants,  all 
favour  this  view ;  and  tend  to  the  conclusion  that 
the  difference  between  animal  and  plant  is  one  of 
degree  rather  than  of  kind,  and  that  the  problem 
whether,  in  a  given  case,  an  organism  is  an 
animal  or  a  plant,  may  be  essentially  insoluble. 


vn 

A  LOBSTER;  OR,  THE  STUDY  OF 

ZOOLOGY 

[1861] 

Natural  History  is  the  name  familiarly  applied 
to  the  study  of  the  properties  of  such  natural 
bodies  as  minerals,  plants,  and  animals;  the 
sciences  which  embody  the  knowledge  man  has 
acquired  upon  these  subjects  are  commonly  termed 
Natural  Sciences,  in  contradistinction  to  other  so- 
called  "  physical "  sciences ;  and  those  who  devote 
themselves  especially  to  the  pursuit  of  such 
sciences  have  been  and  are  commonly  termed 
"  Naturalists." 

Linnaeus  was  a  naturalist  in  this  wide  sense, 
and  his  "  Systema  Naturae "  was  a  work  upon 
natural  history,  in  the  broadest  acceptation  of  the 
term ;  in  it,  that  great  methodising  spirit  em- 
bodied all  that  was  known  in  his  time  of  the 
distinctive    characters   of  minerals,  animals,  and 


VII         TUE  STUDY  OF  ZOOLOGY        197 

plants.  But  the  enormous  stimulus  which 
Linnaeus  gave  to  the  investigation  of  nature  soon 
rendered  it  impossible  that  any  one  man  should 
write  another  "  Systema  Naturae,"  and  extremely 
difficult  for  any  one  to  become  even  a  naturalist 
such  as  Linnaeus  was. 

Great  as  have  been  the  advances  made  by  all 
the  three  branches  of  science,  of  old  included 
under  the  title  of  natural  history,  there  can  be  no 
doubt  that  zoology  and  botany  have  grown  in  an 
enormously  greater  ratio  than  mineralogy;  and 
hence,  as  I  suppose,  the  name  of  "  natural  history  " 
has  gradually  become  more  and  more  definitely 
attached  to  these  prominent  divisions  of  the 
subject,  and  by  "  naturalist "  people  have  meant 
more  and  more  distinctly  to  imply  a  student  of 
the  structure  and  function  of  living  beings. 

However  this  may  be,  it  is  certain  that  the 
advance  of  knowledge  has  gradually  widened  the 
distance  between  mineralogj^  and  its  old  associates, 
while  it  has  drawn  zoology  and  botany  closer  to- 
gether; so  that  of  late  years  it  has  been  found 
convenient  (and  indeed  necessary)  to  associate  the 
sciences  which  deal  with  vitality  and  all  its  phe- 
nomena under  the  common  head  of  "  biology "  ; 
and  the  biologists  have  come  to  repudiate  any 
blood-relationship  with  their  foster-brothers,  the 
mineralogists. 

Certain  broad  laws  have  a  general  application 
throughout  both    the   animal   and   the    vej^etable 


198  THE   STUDY  OF  ZOOLOGY  vil 

worlds,  but  the  ground  common  to  these  kingdoms 
of  nature  is  not  of  very  wide  extent,  and  the 
multiplicity  of  details  is  so  great,  that  the  student 
of  living  beings  finds  himself  obliged  to  devote  his 
attention  exclusively  either  to  the  one  or  the 
other.  If  he  elects  to  study  plants,  under  any 
aspect,  we  know  at  once  what  to  call  him.  He  is 
a  botanist,  and  his  science  is  botany.  But  if  the 
investigation  of  animal  life  be  his  choice,  the  name 
generally  applied  to  him  will  vary  according  to 
the  kind  of  animals  he  studies,  or  the  particular 
phenomena  of  animal  life  to  which  he  confines  his 
attention.  If  the  study  of  man  is  his  object,  he  is 
called  an  anatomist,  or  a  physiologist,  or  an  ethno- 
logist ;  but  if  he  dissects  animals,  or  examines 
into  the  mode  in  which  their  functions  are  per- 
formed, he  is  a  comparative  anatomist  or  com- 
parative physiologist.  If  he  turns  his  attention  to 
fossil  animals,  he  is  a  palaeontologist.  If  his  mind 
is  more  particularly  directed  to  the  specific  de- 
scription, discrimination,  classification,  and  distri- 
bution of  animals,  he  is  termed  a  zoologist. 

For  the  purpose  of  the  present  discourse,  how- 
ever, I  shall  recognise  none  of  these  titles  save  the 
last,  which  I  shall  employ  as  the  equivalent  of 
botanist,  and  I  shall  use  the  term  zoology  as 
denoting  the  whole  doctrine  of  animal  life,  in  con- 
tradistinction to  botany,  which  signifies  the  whole 
doctrine  of  vegetable  life. 

Employed  in  this  sense,  zoology,  like  botany,  is 


VII  THE   STUDY  OF   ZOOLOGY  199 

divisible  into  three  great  but  subordinate  sciences, 
morphology,  physiology,  and  distribution,  each  of 
which  may,  to  a  very  great  extent,  be  studied  in- 
dependently of  the  other. 

Zoological  morphology  is  the  doctrine  of  animal 
form  or  structure.  Anatomy  is  one  of  its  branches ; 
development  is  another  ;  while  classification  is  the 
expression  of  the  relations  which  different  animals 
bear  to  one  another,  in  respect  of  their  anatomy 
and  their  development. 

Zoological  distribution  is  the  study  of  animals  in 
relation  to  the  terrestrial  conditions  which  obtain 
now,  or  have  obtained  at  any  previous  epoch  of 
the  earth's  history. 

Zoological  physiology,  lastly,  is  the  doctrine  of 
the  functions  or  actions  of  animals.  It  regards 
animal  bodies  as  machines  impelled  by  certain 
forces,  and  performing  an  amount  of  work  which 
can  be  expressed  in  terms  of  the  ordinary  forces  of 
nature.  The  final  object  of  physiology  is  to 
deduce  the  facts  of  morphology,  on  the  one  hand, 
and  those  of  distribution  on  the  other,  from  the 
laws  of  the  molecular  forces  of  matter. 

Such  is  the  scope  of  zoology.  But  if  I  were  to 
content  myself  with  the  enunciation  of  these  dry 
definitions,  I  should  ill  exem^phfy  that  method  of 
teaching  this  branch  of  physical  science,  which  it  is 
my  chief  business  to-night  to  recommend.  Let  us 
turn  away  then  from  abstract  definitions.  Let  us 
take  some  concrete  living  thing,  some  animal,  tho 


200  THE   STUDY   OF  ZOOLOGY  vil 

commoner  the  better,  and  let  us  see  how  the  appli- 
cation of  common  sense  and  common  logic  to  the 
obvious  facts  it  presents,  inevitably  leads  us  into 
all  these  branches  of  zoological  science. 

I  have  before  me  a  lobster.  When  I  examine 
it,  what  appears  to  be  the  most  striking  character  it 
presents  ?  Why,  I  observe  that  this  part  which  we 
call  the  tail  of  the  lobster,  is  made  up  of  six  distinct 
hard  rings  and  a  seventh  terminal  piece.  If  I 
separate  one  of  the  middle  rings,  say  the  third,  I 
find  it  carries  upon  its  under  surface  a  pair  of 
Hmbs  or  appendages,  each  of  which  consists  of  a 
stalk  and  two  terminal  pieces.  So  that  I  can  re- 
present a  transverse  section  of  the  ring  and  its 
appendages  upon  the  diagram  board  in  this  way. 

If  I  now  take  the  fourth  ring,  I  find  it  has  the 
same  structure,  and  so  have  the  fifth  and  the  second  ; 
so  that,  in  each  of  these  divisions  of  the  tail,  I  find 
parts  which  correspond  with  one  another,  a  ring 
and  two  appendages ;  and  in  each  appendage  a 
stalk  and  two  end  pieces.  These  corresponding 
parts  are  called,  in  the  technical  language  of 
anatomy,  "homologous  parts."  The  ring  of  the 
third  division  is  the  "  homologue  "  of  the  ring  of 
the  fifth,  the  appendage  of  the  former  is  the  homo- 
logue of  the  appendage  of  the  latter.  And,  as 
each  division  exhibits  corresponding  parts  in 
corresponding  places,  we  say  that  all  the  divisions 
are  constructed  upon  the  same  plan.  But  now  let 
us  consider  the  sixth  division.     It  is  similar  to, 


Til  THE    STUDY   OF   ZOOLOGY  201 

and  yet  diflferent  from,  the  others.  The  ring  is 
essentially  the  same  as  in  the  other  divisions  ;  but 
the  appendages  look  at  first  as  if  they  were  very 
different ;  and  yet  when  we  regard  them  closely, 
what  do  we  find  ?  A  stalk  and  two  terminal 
divisions,  exactly  as  in  the  others,  but  the  stalk  is 
very  short  and  very  thick,  the  terminal  divisions 
are  very  broad  and  flat,  and  one  of  them  is  divided 
into  two  pieces. 

I  may  say,  therefore,  that  the  sixth  segment  is 
like  the  others  in  plan,  but  that  it  is  modified  in 
its  details. 

The  first  segment  is  like  the  others,  so  far  as  its 
ring  is  concerned,  and  though  its  appendages  differ 
from  any  of  those  yet  examined  in  the  simphcity 
of  their  structure,  parts  corresponding  with  the 
stem  and  one  of  the  divisions  of  the  appendages 
of  the  other  segments  can  be  readily  discerned  in 
them. 

Thus  it  appears  that  the  lobster's  tail  is  com- 
posed of  a  series  of  segments  which  are  funda- 
mentally similar,  though  each  presents  peculiar 
modifications  of  the  plan  common  to  all.  But 
when  I  turn  to  the  forepart  of  the  body  I  see,  at 
first,  nothing  but  a  great  shield-like  shell,  called 
technically  the  "  carapace,"  ending  in  front  in  a 
sharp  spine,  on  either  side  of  which  are  the  curious 
compound  eyes,  set  upon  the  ends  of  stout  movable 
stalks.  Behind  these,  on  the  under  side  of  the 
body,  are  two  pairs  of  long  feelers,  or  antennae. 


202  THE   STUDY   OF   ZOOLOGY  vn 

followed  by  six  pairs  of  jaws  folded  against  one 
another  over  the  mouth,  and  five  pairs  of  legs,  the 
foremost  of  these  being  the  great  pinchers,  or 
claws,  of  the  lobster. 

It  looks,  at  first,  a  little  hopeless  to  attempt  to 
find  in  this  complex  mass  a  series  of  rings,  each 
with  its  pair  of  appendages,  such  as  I  have  shown 
you  in  the  abdomen,  and  yet  it  is  not  difiicult  to 
demonstrate  their  existence.  Strip  off  the  legs, 
and  you  will  find  that  each  pair  is  attached  to  a 
very  definite  segment  of  the  under  wall  of  the 
body;  but  these  segments,  instead  of  being  the 
lower  parts  of  free  rings,  as  in  the  tail,  are  such 
parts  of  rings  which  are  all  solidly  united  and 
bound  together  ;  and  the  like  is  true  of  the  jaws, 
the  feelers,  and  the  eye-stalks,  every  pair  of  which 
is  borne  upon  its  own  special  segment.  Thus  the 
conclusion  is  gradually  forced  upon  us,  that  the 
body  of  the  lobster  is  composed  of  as  many  rings 
as  there  are  pairs  of  appendages,  namely,  twenty  in 
all,  but  that  the  six  hindmost  rings  remain  free 
and  movable,  while  the  fourteen  front  rings  be- 
come firmly  soldered  together,  their  backs  forming 
one  continuous  shield — the  carapace. 

Unity  of  plan,  diversity  in  execution,  is  the 
lesson  taught  by  the  study  of  the  rings  of  the  body, 
and  the  same  instruction  is  given  still  more  em- 
phatically by  the  appendages.  If  I  examine  the 
outermost  jaw  I  find  it  consists  of  three  distinct 
portions,  an  inner,  a  middle,  and  an  outer,  mounted 


VII  THE   STUDY  OF   ZOOLOGY  203 

upon  a  common  stem ;  and  if  I  compare  this  jaw 
with  the  legs  behind  it,  or  the  jaws  in  front  of  it, 
I  find  it  quite  easy  to  see,  that,  in  the  legs,  it  is 
the  part  of  the  appendage  which  corresponds  with 
the  inner  division,  which  becomes  modified  into 
what  we  know  familiarly  as  the  "  leg,"  while  the 
middle  division  disappears,  and  the  outer  division 
is  hidden  under  the  carapace.  Nor  is  it  more 
difficult  to  discern  that,  in  the  appendages  of  the 
tail,  the  middle  division  appears  again  and  the 
outer  vanishes ;  while,  on  the  other  hand,  in  the 
foremost  jaw,  the  so-called  mandible,  the  inner 
division  only  is  left ;  and,  in  the  same  way,  the 
parts  of  the  feelers  and  of  the  eye-stalks  can  be 
identified  with  those  of  the  legs  and  jaws. 

But  whither  does  all  this  tend  ?  To  the  very 
remarkable  conclusion  that  a  unity  of  plan,  of  the 
same  kind  as  that  discoverable  in  the  tail  or 
abdomen  of  the  lobster,  pervades  the  whole  organ- 
isation of  its  skeleton,  so  that  I  can  return  to  the 
diagram  representing  any  one  of  the  rings  of  the 
tail,  which  I  drew  upon  the  board,  and  by  adding  a 
third  division  to  each  appendage,  I  can  use  it  as  a 
sort  of  scheme  or  plan  of  any  ring  of  the  body.  I 
can  give  names  to  all  the  parts  of  that  figure,  and 
then  if  I  take  any  segment  of  the  body  of  the 
lobster,  I  can  point  out  to  you  exactly,  what  modi- 
fication the  general  plan  has  undergone  in  that 
particular  segment ;  what  part  has  remained 
movable,  and  what  has  become  fixed  to  another ; 


204  THE   STUDY   OF   ZOOLOGY  tii 

what  has  been  excessively  developed  and  metamor- 
phosed and  what  has  been  suppressed. 

But  I  imagine  I  hear  the  question,  How  is  all 
this  to  be  tested  ?  No  doubt  it  is  a  pretty  and 
ingenious  way  of  looking  at  the  structure  of  any 
animal ;  but  is  it  anything  more  ?  Does  Nature 
acknowledge,  in  any  deeper  way,  this  unity  of  plan 
we  seem  to  trace  ? 

The  objection  suggested  by  these  questions  is  a 
very  vahd  and  important  one,  and  morphology  was 
in  an  unsound  state  so  long  as  it  rested  upon  the 
mere  perception  of  the  analogies  which  obtain 
between  fully  formed  parts.  The  unchecked  in- 
genuity of  speculative  anatomists  proved  itself 
fully  competent  to  spin  any  number  of  contradic- 
tory hypotheses  out  of  the  same  facts,  and  endless 
morphological  dreams  threatened  to  supplant 
scientific  theory. 

Happily,  however,  there  is  a  criterion  of  mor- 
phological truth,  and  a  sure  test  of  all  homologies. 
Our  lobster  has  not  always  been  what  we  see  it ; 
it  was  once  an  egg,  a  semifluid  mass  of  3'olk,  not  so 
big  as  a  pin's  head,  contained  in  a  transparent 
membrane,  and  exhibiting  not  the  least  trace  of 
any  one  of  those  organs,  the  multiplicity  and 
complexity  of  which,  in  the  adult,  are  so  surprising. 
After  a  time,  a  delicate  patch  of  cellular  membrane 
appeared  upon  one  face  of  this  yolk,  and  that 
patch  was  the  foundation  of  the  whole  creature, 
the   clay   out   of  which    it   would    be    moulded. 


vn         THE  STUDY  OF  ZOOLOGY        205 

Gradually  investing  the  yolk,  it  became  subdivided 
by  transverse  constrictions  into  segments,  the 
forerunners  of  the  rings  of  the  body.  Upon  the 
ventral  surface  of  each  of  the  rings  thus  sketched 
out,  a  pair  of  bud-like  prominences  made  their  ap- 
pearance— the  rudiments  of  the  appendages  of  the 
ring.  At  first,  all  the  appendages  were  alike,  but, 
as  they  grew,  most  of  them  became  distinguished 
into  a  stem  and  two  terminal  divisions,  to  which, 
in  the  middle  part  of  the  body,  was  added  a  third 
outer  division ;  and  it  was  only  at  a  later  period, 
that  by  the  modification,  or  absorption,  of  certain 
of  these  primitive  constituents,  the  limbs  acquired 
their  perfect  form. 

Thus  the  study  of  development  proves  that  the 
doctrine  of  unity  of  plan  is  not  merely  a  fancy, 
that  it  is  not  merely  one  way  of  looking  at  the 
matter,  but  that  it  is  the  expression  of  deep-seated 
natural  facts.  The  legs  and  jaws  of  the  lobster 
may  not  merely  be  regarded  as  modifications  of  a 
common  type, — in  fact  and  in  nature  they  are  so, 
— the  leg  and  the  jaw  of  the  young  animal  being, 
at  first,  indistinguishable. 

These  are  wonderful  truths,  the  more  so  because 
the  zoologist  finds  them  to  be  of  universal  appHca- 
tion.  The  investigation  of  a  pol}^e,  of  a  snail,  of 
a  fish,  of  a  horse,  or  of  a  man,  would  have  led  us, 
though  by  a  less  easy  path,  perhaps,  to  exactly  the 
same  point.  Unity  of  plan  everjrvs^here  Kes  hidden 
under  the  mask   of  diversity   of  structure — the 


206  THE   STUDY   OF  ZOOLOGY  vii 

complex  is  ever^^vhere  evolved  out  of  the  simple. 
Every  animal  has  at  first  the  form  of  an  egg,  and 
every  animal  and  every  organic  part,  in  reaching 
its  adult  state,  passes  through  conditions  common 
to  other  animals  and  other  adult  parts ;  and  this 
leads  me  to  another  point.  I  have  hitherto 
spoken  as  if  the  lobster  were  alone  in  the  world, 
but,  as  I  need  hardly  remind  you,  there  are 
m3rriads  of  other  animal  organisms.  Of  these, 
some,  such  as  men,  horses,  birds,  fishes,  snails, 
slugs,  oysters,  corals,  and  sponges,  are  not  in  the 
least  Hke  the  lobster.  But  other  animals,  though 
they  may  differ  a  good  deal  from  the  lobster,  are 
yet  either  very  hke  it,  or  are  hke  something  that 
is  hke  it.  The  cray  fish,  the  rock  lobster,  and  the 
pra^vn,  and  the  shrimp,  for  example,  however 
different,  are  yet  so  hke  lobsters,  that  a  child 
would  group  them  as  of  the  lobster  kind,  in  contra- 
distinction to  snails  and  slugs  ;  and  these  last  again 
would  form  a  kind  by  themselves,  in  contradis- 
tinction to  cows,  horses,  and  sheep,  the  cattle  kind. 

But  this  spontaneous  grouping  into  "  kinds  "  is 
the  first  essay  of  the  human  mind  at  classification, 
or  the  calhng  by  a  common  name  of  those  things 
that  are  ahke,  and  the  arranging  them  in  such  a 
manner  as  best  to  suggest  the  sum  of  their  hke- 
nesses  and  unhkenesses  to  other  things. 

Those  kinds  which  include  no  other  subdivisions 
than  the  sexes,  or  various  breeds,  are  called,  in 
techni<;al  language,  species.     The  Enghsh  lobster 


VII         THE  STUDY  OF  ZOOLOGY        207 

is  a  species,  our  cray  fish  is  another,  our  prawn  is 
another.  In  other  countries,  however,  there  are 
lobsters,  cray  fish,  and  prawns,  very  Hke  ours,  and 
yet  presenting  sufficient  differences  to  deserve  dis- 
tinction. Naturahsts,  therefore,  express  this  re- 
semblance and  this  diversity  by  grouping  them  as 
distinct  species  of  the  same  "genus."  But  the 
lobster  and  the  cray  fish,  though  belonging  to  dis- 
tinct genera,  have  many  features  in  common,  and 
hence  are  grouped  together  in  an  assemblage  which 
is  called  a  family.  More  distant  resemblances 
connect  the  lobster  with  the  prawn  and  the  crab, 
which  are  expressed  by  putting  all  these  into  the 
same  order.  Again,  more  remote,  but  still  very 
definite,  resemblances  unite  the  lobster  with  the 
woodlouse,  the  king  crab,  the  water  flea,  and  the 
barnacle,  and  separate  them  firom  all  other  animals ; 
whence  they  collectively  constitute  the  larger 
group,  or  class,  Crustacea.  But  the  Cintstacea 
exhibit  many  pecuHar  features  in  common  with 
insects,  spiders,  and  centipedes,  so  that  these  are 
grouped  into  the  still  larger  assemblage  or  "  pro- 
vince" Articulata;  and,  finally,  the  relations 
which  these  have  to  worms  and  other  lower 
animals,  are  expressed  by  combining  the  whole  vast 
aggregate  into  the  sub-kingdom  of  Annulosa. 

If  I  had  worked  my  way  from  a  sponge  instead 
of  a  lobster,  I  should  have  found  it  associated,  by 
like  ties,  with  a  great  number  of  other  animals 
into  the  sub-kingdom  Protozoa ;  if  I  had  selected 
a  fresh-water  pol^^e  or  a  coral,  the  members  of 


208  THE   STUDY   OF   ZOOLOGY  vii 

what  naturalists  term  the  sub-kingdom  Ccelenterata, 
would  have  grouped  themselves  around  my  type ; 
had  a  snail  been  chosen,  the  inhabitants  of  all 
univalve  and  bivalve,  land  and  water,  shells,  the 
lamp  shells,  the  squids,  and  the  sea-mat  would 
have  gradually  linked  themselves  on  to  it  as  mem- 
bers of  the  same  sub-kingdom  of  Mollusca ;  and 
finally,  starting  from  man,  I  should  have  been  com- 
pelled to  admit  first,  the  ape,  the  rat,  the  horse, 
the  dog,  into  the  same  class ;  and  then  the  bird, 
the  crocodile,  the  turtle,  the  frog,  and  the  fish, 
into  the  same  sub-kingdom  of  Vertehrata. 

And  if  I  had  followed  out  all  these  various  Hues 
of  classification  fully,  I  should  discover  in  the  end 
that  there  was  no  animal,  either  recent  or  fossil, 
which  did  not  at  once  fall  into  one  or  other  of 
these  sub-kingdoms.  In  other  words,  every  animal 
is  organised  upon  one  or  other  of  the  five,  or  more, 
plans,  the  existence  of  which  renders  our  classifi- 
cation possible.  And  so  definitely  and  precisely 
marked  is  the  structure  of  each  animal,  that,  in 
the  present  state  of  our  knowledge,  there  is  not 
the  least  evidence  to  prove  that  a  form,  in 
the  slightest  degree  transitional  between  any  of 
the  two  groups  Vertehrata,  AnmUosa,  Mollusca, 
and  Codenterata,  either  exists,  or  has  existed, 
during  that  period  of  the  earth's  history  which  is 
recorded  by  the  geologist.^  Nevertheless,  you 
must  not  for  a  moment  suppose,  because  no  such 

P  The  different  grouping  necessitated  by  later  knowledge 
does  not  affect  the  principle  of  the  argument. — 1894.] 


vn         THE  STUDY  OF  ZOOLOGY        209 

transitional  forms  are  known,  that  the  members  of 
the  sub-kingdoms  are  disconnected  from,  or  inde- 
pendent of,  one  another.  On  the  contrary,  in 
their  earliest  condition  they  are  all  similar,  and  the 
primordial  germs  of  a  man,  a  dog,  a  bird,  a  fish,  a 
beetle,  a  snail,  and  a  polype  are,  in  no  essential 
structural  respects,  distinguishable. 

In  this  broad  sense,  it  may  with  truth  be  said, 
that  all  Hving  animals,  and  all  those  dead  faunae 
which  geology  reveals,  are  bound  together  by  an 
all-pervading  unity  of  organisation,  of  the  same 
character,  though  not  equal  in  degree,  to  that 
which  enables  us  to  discern  one  and  the  same  plan 
amidst  the  twenty  different  segments  of  a  lobster's 
body.  Truly  it  has  been  said,  that  to  a  clear  eye 
the  smallest  fact  is  a  window  through  which  the 
Infinite  may  be  seen. 

Turning  from  these  purely  morphological  con- 
siderations, let  us  now  examine  into  the  manner  in 
which  the  attentive  study  of  the  lobster  impels  us 
into  other  lines  of  research. 

Lobsters  are  found  in  all  the  European  seas ; 
but  on  the  opposite  shores  of  the  Atlantic  and  in 
the  seas  of  the  southern  hemisphere  they  do  not 
exist.  They  are,  however,  represented  in  these 
regions  by  very  closely  allied,  but  distinct  forms — 
the  Hcmarus  Amcricaniis  and  the  Homarus 
Capensis :  so  that  we  may  say  that  the  European 
has  one  species  of  Homarus;  the  American, 
another;    the    African,   another;    and    thus    the 

200 


210  THE   STUDY   OF  ZOOLOGY  vn 

remarkable  facts  of  geographical  distribution  begin 
to  dawn  upon  us. 

Again,  if  we  examine  the  contents  of  the  earth's 
crust,  we  shall  find  in  the  latter  of  those  deposits, 
which  have  served  as  the  great  burjdng  groimds  of 
past  ages,  numberless  lobster-hke  animals,  but 
none  so  similar  to  our  living  lobster  as  to  make 
zoologists  sure  that  they  belonged  even  to  the 
same  genus.  If  we  go  still  further  back  in  time, 
we  discover,  in  the  oldest  rocks  of  all,  the  remains 
of  animals,  constructed  on  the  same  general  plan 
as  the  lobster,  and  belonging  to  the  same  great 
group  of  Crustacea;  but  for  the  most  part 
totally  different  from  the  lobster,  and  indeed  from 
any  other  living  form  of  crustacean ;  and  thus  we 
gain  a  notion  of  that  successive  change  of  the 
animal  population  of  the  globe,  in  past  ages, 
which  is  the  most  striking  fact  revealed  by 
geology. 

Consider,  now,  where  our  inquiries  have  led  us. 
We  studied  our  type  morphologically,  when  we 
determined  its  anatomy  and  its  development,  and 
when  comparing  it,  in  these  respects,  with  other 
animals,  we  made  out  its  place  in  a  system  of 
classification.  If  we  were  to  examine  every 
animal  in  a  similar  manner,  we  should  estabhsh  a 
complete  body  of  zoological  morphology. 

Again,  we  investigated  the  distribution  of  our 
type  in  space  and  in  time,  and,  if  the  Hke  had 
been  done  with  every  animal,  the  sciences  of  geo- 


ril  THE   STUDY   OF  ZOOLOGY  211 

graphical  and  geological  distribution  would  have 
attained  their  hmit. 

But  you  will  observe  one  remarkable  circum- 
stance, that,  up  to  this  point,  the  question  of  the 
life  of  these  organisms  has  not  come  under  con- 
sideration. Morphology  and  distribution  might  be 
studied  almost  as  well,  if  animals  and  plants  were 
a  peculiar  kind  of  crystals,  and  possessed  none  of 
those  functions  which  distinguish  living  beings  so 
remarkably.  But  the  facts  of  morphology  and 
distribution  have  to  be  accounted  for,  and  the 
science,  the  aim  of  which  it  is  to  account  for 
them,  is  Physiolog}'. 

Let  us  return  to  our  lobster  once  more.  If  we 
watched  the  creature  in  its  native  element,  we 
should  see  it  climbing  actively  the  submerged 
rocks,  among  which  it  delights  to  live,  by  means 
of  its  strong  legs ;  or  swimming  by  powerful  strokes 
of  its  great  tail,  the  appendages  of  the  sixth 
joint  of  which  are  spread  out  into  a  broad  fan-like 
propeller :  seize  it,  and  it  will  show  you  that  its 
great  claws  are  no  mean  weapons  of  offence ;  sus- 
pend a  piece  of  carrion  among  its  haunts,  and  it 
will  greedily  devour  it,  tearing  and  crushing  the 
flesh  by  means  of  its  multitudinous  jaws. 

Suppose  that  we  had  known  nothing  of  the 
lobster  but  as  an  inert  mass,  an  organic  crystal,  if 
I  may  use  the  phrase,  and  that  we  could  suddenly 
see  it  exerting  all  these  powers,  what  wonderful 
new  ideas  and  new  questions  would  arise  in  our 


212  THE  STUDY   OF   ZOOLOGY  vii 

minds  !  The  great  new  question  would  be,  "  How 
does  all  this  take  place  ? "  the  chief  new  idea  would 
be,  the  idea  of  adaptation  to  purpose, — the  notion, 
that  the  constituents  of  animal  bodies  are  not 
mere  unconnected  parts,  but  organs  working 
together  to  an  end.  Let  us  consider  the  tail  of 
the  lobster  again  from  this  point  of  view. 
Morphology  has  taught  us  that  it  is  a  series 
of  segments  composed  of  homologous  parts, 
which  undergo  various  modifications — beneath 
and  through  which  a  common  plan  of  formation 
is  discernible.  But  if  I  look  at  the  same  part 
physiologically,  I  see  that  it  is  a  most  beautifully 
constructed  organ  of  locomotion,  by  means  of 
which  the  animal  can  swiftly  propel  itself  either 
backwards  or  forwards. 

But  how  is  this  remarkable  propulsive  machine 
made  to  perform  its  functions  ?  If  I  were  sud- 
denly to  kill  one  of  these  animals  and  to  take  out 
all  the  soft  parts,  I  should  find  the  shell  to  be  per- 
fectly inert,  to  have  no  more  power  of  moving 
itself  than  is  possessed  by  the  machinery  of  a  mill 
when  disconnected  from  its  steam-engine  or  water- 
wheel.  But  if  I  were  to  open  it,  and  take  out  the 
viscera  only,  leaving  the  white  flesh,  I  should  per- 
ceive that  the  lobster  could  bend  and  extend  its 
tail  as  well  as  before.  If  I  were  to  cut  off  the 
tail,  I  should  cease  to  find  any  spontaneous  motion 
in  it ;  but  on  pinching  any  portion  of  the  flesh, 
I  should  observe  that  it  underwent  a  very  curious 


vn         THE  STUDY  OF  ZOOLOGY        213 

change — each  fibre  becoming  shorter  and  thicker. 
By  this  act  of  contraction,  as  it  is  termed,  the 
parts  to  which  the  ends  of  the  fibre  are  attached 
are,  of  course,  approximated  ;  and  according  to  the 
relations  of  their  points  of  attachment  to  the 
centres  of  motions  of  the  different  rings,  the 
bending  or  the  extension  of  the  tail  results.  Close 
observation  of  the  newly-opened  lobster  would 
soon  show  that  all  its  movements  are  due  to  the 
same  cause — the  shortening  and  thickening  of 
these  fleshy  fibres,  which  are  technically  called 
muscles. 

Here,  then,  is  a  capital  fact.  The  movements 
of  the  lobster  are  due  to  muscular  contractiHty. 
But  why  does  a  muscle  contract  at  one  time  and 
not  at  another  ?  Why  does  one  whole  group  of 
muscles  contract  when  the  lobster  wishes  to  ex- 
tend his  tail,  and  another  group  when  he  desires 
to  bend  it  ?  What  is  it  originates,  directs,  and 
controls  the  motive  power  ? 

Experiment,  the  great  instrument  for  the  ascer- 
tainment of  truth  in  physical  science,  answers  this 
question  for  us.  In  the  head  of  the  lobster 
there  lies  a  small  mass  of  that  pecuHar  tissue 
which  is  known  as  nervous  substance.  Cords  of 
similar  matter  connect  this  brain  of  the  lobster, 
directly  or  indirectly,  with  the  muscles.  Now,  if 
these  communicating  cords  are  cut,  the  brain 
remaining  entire,  the  power  of  exerting  what  we 
call  voluntary  motion  in  the  parts  below  the  sec- 


214  THE   STUDY   OF  ZOOLOGY  Til 

tion  is  destroyed ;  and,  on  the  other  hand,  if,  the 
cords  remaining  entire,  the  brain  mass  be  destroyed, 
the  same  voluntary  mobihty  is  equally  lost. 
Whence  the  inevitable  conclusion  is,  that  the 
power  of  originating  these  motions  resides  in 
the  brain  and  is  propagated  along  the  nervous 
cords. 

In  the  higher  animals  the  phenomena  which 
attend  this  transmission  have  been  investigated, 
and  the  exertion  of  the  pecuhar  energy  which 
resides  in  the  nerves  has  been  found  to  be  accom- 
panied by  a  disturbance  of  the  electrical  state  of 
their  molecules. 

If  we  could  exactly  estimate  the  signification 
of  this  disturbance ;  if  we  could  obtain  the  value 
of  a  given  exertion  of  nerve  force  by  determining 
the  quantity  of  electricity,  or  of  heat,  of  which  it 
is  the  equivalent;  if  we  could  ascertain  upon 
what  arrangement,  or  other  condition  of  the 
molecules  of  matter,  the  manifestation  of  the 
nervous  and  muscular  energies  depends  (and 
doubtless  science  wiU  some  day  or  other  ascertain 
these  points),  physiologists  would  have  attained 
their  ultimate  goal  in  this  direction ;  they  would 
have  determined  the  relation  of  the  motive  force 
of  animals  to  the  other  forms  of  force  found  in 
nature  ;  and  if  the  same  process  had  been  success- 
fully performed  for  all  the  operations  which  are 
carried  on  in,  and  by,  the  animal  frame,  physiology 
would  be  perfect,  and  the  facts  of  morphology 


VII  THE   STUDY   OF   ZOOLOGY  215 

and  distribution  would  be  deducible  from  the 
laws  which  physiologists  had  established,  com- 
bined with  those  determining  the  condition  of  the 
surrounding  universe. 

There  is  not  a  fragment  of  the  organism  of  this 
humble  animal  whose  study  would  not  lead  us 
into  regions  of  thought  as  large  as  those  which  I 
have  briefly  opened  up  to  you ;  but  what  I  have 
been  saying,  I  trust,  has  not  only  enabled  you  to 
form  a  conception  of  the  scope  and  purport  of 
zoology,  but  has  given  you  an  imperfect  example 
of  the  manner  in  which,  in  my  opinion,  that 
science,  or  indeed  any  physical  science,  may  be 
best  taught.  The  great  matter  is,  to  make 
teaching  real  and  practical,  by  fixing  the  atten- 
tion of  the  student  on  particular  facts;  but  at 
the  same  time  it  should  be  rendered  broad  and 
comprehensive,  by  constant  reference  to  the 
generalisations  of  which  all  particular  facts  are 
illustrations.  The  lobster  has  served  as  a  type 
of  the  whole  animal  kingdom,  and  its  anatomy 
and  physiology  have  illustrated  for  us  some  of 
the  greatest  truths  of  biology.  The  student  who 
has  once  seen  for  himself  the  facts  which  I  have 
described,  has  had  their  relations  explained  to 
him,  and  has  clearly  comprehended  them,  has, 
so  far,  a  knowledge  of  zoology,  which  is  real  and 
genuine,  however  limited  it  may  be,  and  which  is 
worth  more  than  all  the  mere  reading  knowledge 
of  the  science  he  could  ever  acquire.    His  zoologi* 


216  THE   STUDY  OF   ZOOLOGY  vii 

cal  information  is,  so  far,  knowledge  and  not  mere 
hearsay. 

And  if  it  were  my  business  to  fit  you  for  the 
certificate  in  zoological  science  granted  by  this 
department,  I  should  pursue  a  course  precisely 
similar  in  principle  to  that  which  I  have  taken 
to-night.  I  should  select  a  fresh- water  sponge, 
a  fresh-water  pol}^e  or  a  Cyancea,  a  fi:esh-water 
mussel,  a  lobster,  a  fowl,  as  tj^es  of  the  five 
primary  divisions  of  the  animal  kingdom.  I 
should  explain  their  structure  very  fully,  and 
show  how  each  illustrated  the  great  principles  of 
zoology.  Having  gone  very  carefully  and  fully 
over  this  ground,  I  should  feel  that  you  had  a 
safe  foundation,  and  I  should  then  take  you  in 
the  same  way,  but  less  minutely,  over  similarly 
selected  illustrative  types  of  the  classes ;  and  then 
I  should  direct  your  attention  to  the  special 
forms  enumerated  under  the  head  of  types,  in 
this  syllabus,  and  to  the  other  facts  there  men- 
tioned. 

That  would,  speaking  generally,  be  my  plan. 
But  I  have  undertaken  to  explain  to  you  the  best 
mode  of  acquiring  and  communicating  a  know- 
ledge of  zoology,  and  you  may  therefore  fairly  ask 
me  for  a  more  detailed  and  precise  account  of  the 
manner  in  which  I  should  propose  to  furnish  you 
with  the  information  I  refer  to. 

My  own  impression  is,  that  the  best  model  for 
aU  kinds  of  training  in  physical  science  is  that 


vu  TnE  STUDY  OF  ZOOLOGY        217 

afforded  by  the  method  of  teaching  anatomy,  in 
use  in  the  medical  schools.  This  method  con- 
sists of  three  elements — lectures,  demonstrations, 
and  examinations. 

The  object  of  lectures  is,  in  the  fimh  place,  to 
awaken  the  attention  and  excite  the  enthusiasm 
of  the  student;  and  this,  I  am  sure,  may  be 
effected  to  a  far  greater  extent  by  the  oral  dis- 
course and  by  the  personal  influence  of  a  respected 
teacher  than  in  any  other  way.  Secondly,  lectures 
have  the  double  use  of  guiding  the  student  to 
the  salient  points  of  a  subject,  and  at  the  same 
time  forcing  him  to  attend  to  the  whole  of  it,  and 
not  merely  to  that  part  which  takes  his  fancy. 
And  lastly,  lectures  afford  the  student  the  oppor- 
tunity of  seeking  explanations  of  those  difficulties 
which  will,  and  indeed  ought  to,  arise  in  the 
course  of  his  studies. 

What  books  shall  I  read  ?  is  a  question  con- 
stantly put  by  the  student  to  the  teacher.  My 
reply  usually  is,  "  None :  write  your  notes  out 
carefully  and  fully ;  strive  to  understand  them 
thoroughly;  come  to  me  for  the  explanation  of 
anything  you  cannot  understand ;  and  I  would 
rather  you  did  not  distract  your  mind  by  reading." 
A  properly  composed  course  of  lectures  ought  to 
contain  fully  as  much  matter  as  a  student  can 
assimilate  in  the  time  occupied  by  its  delivery; 
and  the  teacher  should  always  recollect  that  his 
business  is  to  feed,  and  not  to  cram  the  intellect. 


218        THE  STUDY  OF  ZOOLOGY         vn 

Indeed,  I  believe  that  a  student  who  gains 
from  a  course  of  lectures  the  simple  habit  of 
concentrating  his  attention  upon  a  definitely 
limited  series  of  facts,  until  they  are  thoroughly 
mastered,  has  made  a  step  of  immeasurable 
importance. 

But,  however  good  lectures  may  be,  and  how- 
ever extensive  the  course  of  reading  by  which 
they  are  followed  up,  they  are  but  accessories  to 
the  great  instrument  of  scientific  teaching — 
demonstration.  If  I  insist  unweariedly,  nay 
fanatically,  upon  the  importance  of  physical 
science  as  an  educational  agent,  it  is  because 
the  study  of  any  branch  of  science,  if  properly 
conducted,  appears  to  me  to  fill  up  a  void  left 
by  all  other  means  of  education.  I  have  the 
greatest  respect  and  love  for  literature;  nothing 
would  grieve  me  more  than  to  see  hterary  train- 
ing other  than  a  very  prominent  branch  of 
education :  indeed,  I  wish  that  real  literarj^  dis- 
cipline were  far  more  attended  to  than  it  is ; 
but  I  cannot  shut  my  eyes  to  the  fact,  that  there 
is  a  vast  difference  between  men  who  have  had  a 
purely  literary,  and  those  who  have  had  a  sound 
scientific,  training. 

Seeking  for  the  cause  of  this  difference,  I 
imagine  I  can  find  it  in  the  fact  that,  in  the 
world  of  letters,  learning  and  knowledge  are  one, 
and  books  are  the  source  of  both;  whereas  in 
science,  as  in  life,  learning   and   knowledge   are 


vil  THE   STUDY   OF   ZOOLOGY  219 

distinct,  and  the  study  of  things,  and  not  of 
books,  is  the  source  of  the  latter. 

All  that  literature  has  to  bestow  may  be  obtained 
by  reading  and  by  practical  exercise  in  writing 
and  in  speaking ;  but  I  do  not  exaggerate  when 
I  say,  that  none  of  the  best  gifts  of  science  are  to 
be  won  by  these  means.  On  the  contrary,  the 
great  benefit  w^hich  a  scientific  education  bestows, 
whether  as  training  or  as  knowledge,  is  dependent 
U23on  the  extent  to  w^hich  the  mind  of  the  student 
is  brought  into  immediate  contact  with  facts — • 
upon  the  degree  to  which  he  learns  the  habit  of 
appealing  directly  to  Nature,  and  of  acquiring 
through  his  senses  concrete  images  of  those  pro- 
perties of  things,  which  are,  and  always  wiU  be, 
but  approximatively  expressed  in  human  language. 
Our  way  of  looking  at  Nature,  and  of  speaking 
about  her,  varies  from  year  to  year;  but  a  fact 
once  seen,  a  relation  of  cause  and  effect,  once 
demonstratively  apjDrehended,  are  possessions 
which  neither  change  nor  pass  away,  but,  on  the 
contrary,  form  fixed  centres,  about  which  other 
truths  aggregate  by  natural  afiinity. 

Therefore,  the  great  business  of  the  scientific 
teacher  is,  to  imprint  the  fundamental,  irrefragable 
facts  of  his  science,  not  only  by  words  upon  the 
mind,  but  by  sensible  impressions  upon  the  eye, 
and  ear,  and  touch  of  the  student,  in  so  complete 
a  manner,  that  every  term  used,  or  law  enunciated, 
should   afterwards   call   up   vivid   images  of  tho 


220  THE   STUDY   OF   ZOOLOGY  vii 

particular  structural,  or  other,  facts  which  furnished 
the  demonstration  of  the  law,  or  the  illustration 
of  the  term. 

Now  this  important  operation  can  only  be 
achieved  by  constant  demonstration,  which  may 
take  place  to  a  certain  imperfect  extent  during  a 
lecture,  but  which  ought  also  to  be  carried  on 
independently,  and  which  should  be  addressed  to 
each  individual  student,  the  teacher  endeavouring, 
not  so  much  to  show  a  thing  to  the  learner,  as  to 
make  him  see  it  for  himself 

I  am  well  aware  that  there  are  great  practical 
difficulties  in  the  way  of  effectual  zoological 
demonstrations.  The  dissection  of  animals  is  not 
altogether  pleasant,  and  requires  much  time ;  nor 
is  it  easy  to  secure  an  adequate  supply  of  the 
needful  specimens.  The  botanist  has  here  a 
great  advantage ;  his  specimens  are  easily  ob- 
tained, are  clean  and  wholesome,  and  can  be 
dissected  in  a  private  house  as  well  as  anywhere 
else ;  and  hence,  I  believe,  the  fact,  that  botany 
is  so  much  more  readily  and  better  taught  than 
its  sister  science.  But,  be  it  difficult  or  be  it 
easy,  if  zoological  science  is  to  be  properly  studied, 
demonstration,  and,  consequently,  dissection,  must 
be  had.  Without  it,  no  man  can  have  a  reall}^ 
sound  knowledge  of  animal  organisation. 

A  good  deal  may  be  done,  however,  without 
actual  dissection  on  the  student's  part,  by  demon- 
stration upon  specimens  and  preparations ;  and  in 


vn         THE  STUDY  OF  ZOOLOGY        221 

all  probability  it  would  not  be  very  difficult,  were 
the  demand  sufficient,  to  organise  collections  of 
such  objects,  sufficient  for  all  the  purposes  of 
elementary  teaching,  at  a  comparatively  cheap 
rate.  Even  without  these,  much  mis^ht  be 
effected,  if  the  zoological  collections,  which  are 
open  to  the  public,  were  arranged  according  to 
what  has  been  termed  the  "  typical  principle  " ; 
that  is  to  say,  if  the  specimens  exposed  to  public 
view  were  so  selected  that  the  public  could  learn 
something  from  them,  instead  of  being,  as  at 
present,  merely  confused  by  their  multiplicity. 
For  example,  the  grand  ornithological  gallery  at 
the  British  Museum  contains  between  two  and 
three  thousand  species  of  birds,  and  sometimes 
five  or  six  specimens  of  a  species.  They  are 
very  pretty  to  look  at,  and  some  of  the  cases  are, 
indeed,  splendid ;  but  I  will  undertake  to  say, 
that  no  man  but  a  professed  ornithologist  has 
ever  gathered  much  information  from  the  col- 
lection. Certainly,  no  one  of  the  tens  of  thousands 
of  the  general  public  who  have  walked  through 
that  gallery  ever  knew  more  about  the  essential 
peculiarities  of  birds  when  he  left  the  gallery 
than  when  he  entered  it.  But  if,  somewhere  in 
that  vast  hall,  there  were  a  few  preparations, 
excmphfying  the  leading  structural  peculiarities 
and  the  mode  of  development  of  a  common  fowl ; 
if  the  types  of  the  genera,  the  leading  modifica- 
tions in  the  skeleton,  in  the  plumage  at  various 


222  THE   STUDY   OF   ZOOLOGY  vil 

ages,  in  the  mode  of  nidification,  and  the  hke, 
among  birds,  were  disj^layed  ;  and  if  the  other 
specimens  were  put  away  in  a  place  where  the 
men  of  science,  to  whom  they  are  alone  useful, 
could  have  free  access  to  them,  I  can  conceive 
that  this  collection  might  become  a  great  instru- 
ment of  scientific  education. 

The  last  implement  of  the  teacher  to  which  I 
have  adverted  is  examination — a  means  of  educa- 
tion now  so  thoroughly  understood  that  I  need 
hardly  enlarge  upon  it.  I  hold  that  both  written 
and  oral  examinations  are  indisj^ensable,  and,  by 
requiring  the  description  of  specimens,  they  may 
be  made  to  supplement  demonstration. 

Such  is  the  fullest  reply  the  time  at  m}^  dis- 
posal will  allow  me  to  give  to  the  question — how 
may  a  knowledge  of  zoology  be  best  acquired  and 
communicated  ? 

But  there  is  a  previous  question  which  may 
be  moved,  and  which,  in  fact,  I  know  many 
are  inclined  to  move.  It  is  the  question,  why 
should  teachers  be  encouraged  to  acquire  a  know- 
ledge of  this,  or  any  other  branch  of  physical 
science  ?  What  is  the  use,  it  is  said,  of  attempt- 
ing to  make  physical  science  a  branch  of  primary 
education  ?  Is  it  not  probable  that  teachers,  in 
pursuing  such  studies,  will  be  led  astray  from  the 
acquirement  of  more  important  but  less  attractive 
knowledge  ?  And,  even  if  they  can  learn  some- 
thing of  science  without  prejudice  to  their  useful- 


VII 


THE   STUDY  OF  ZOOLOGY  223 


ness,  what  is  the  good  of  their  attempting  to 
instil  that  knowledge  into  boys  whose  real  busi- 
ness is  the  acquisition  of  reading,  writing,  and 
arithmetic  ? 

These  questions  are,  and  will  be,  very  commonly 
asked,  for  they  arise  from  that  profound  ignorance 
of  the  value  and  true  position  of  physical  science, 
which  infests  the  minds  of  the  most  highly  edu- 
cated and  intelligent  classes  of  the  community. 
But  if  I  did  not  feel  well  assured  that  they  are 
capable  of  being  easily  and  satisfactorily  answered ; 
that  they  have  been  answered  over  and  over  again ; 
and  that  the  time  will  come  when  men  of  Hberal 
education  will  blush  to  raise  such  questions — I 
should  be  ashamed  of  my  position  here  to-night. 
Without  doubt,  it  is  your  great  and  very  important 
function  to  carry  out  elementary  education ;  with- 
out question,  anything  that  should  interfere  with 
the  faithful  fulfilment  of  that  duty  on  your  part 
would  be  a  great  evil ;  and  if  I  thought  that  your 
acquirement  of  the  elements  of  physical  science, 
and  your  communication  of  those  elements  to  your 
pupils,  involved  any  sort  of  interference  with  your 
proper  duties,  I  should  be  the  first  person  to  pro- 
test against  your  being  encouraged  to  do  anything 
of  the  kind. 

But  is  it  true  that  the  acquisition  of  such  a 
knowledge  of  science  as  is  proposed,  and  the  com- 
munication of  that  knowledge,  axe  calculated  to 
weaken  your  usefulness  ?     Or  may  I  not  rather 


224  THE   STUDY   OF  ZOOLOGY  vil 

ask,  18  it  possible  for  you  to  discharge  youi 
functions  properly  without  these  aids  ? 

What  is  the  purpose  of  primary  intellectual 
education  ?  I  apprehend  that  its  first  object  is  to 
train  the  young  in  the  use  of  those  tools  where- 
with men  extract  knowledge  from  the  ever-shift- 
ing succession  of  phenomena  which  pass  before 
their  eyes ;  and  that  its  second  object  is  to  inform 
them  of  the  fundamental  laws  which  have  been 
found  by  experience  to  govern  the  course  of  things, 
so  that  they  may  not  be  turned  out  into  the  world 
naked,  defenceless,  and  a  prey  to  the  events  they 
might  control. 

A  boy  is  taught  to  read  his  own  and  other 
languages,  in  order  that  he  may  have  access  to 
infinitely  wider  stores  of  knowledge  than  could 
ever  be  opened  to  him  by  oral  intercourse  with  his 
fellow  men ;  he  learns  to  write,  that  his  means  of 
communication  with  the  rest  of  mankind  may  be 
indefinitely  enlarged,  and  that  he  may  record  and 
store  up  the  knowledge  he  acquires.  He  is  taught 
elementary  mathematics,  that  he  may  understand 
all  those  relations  of  number  and  form,  upon  which 
the  transactions  of  men,  associated  in  compHcated 
societies,  are  built,  and  that  he  may  have  some 
practice  in  deductive  reasoning. 

All  these  operations  of  reading,  writing,  and 
ciphering,  are  intellectual  tools,  whose  use  should, 
before  all  things,  be  learned,  and  learned  thor- 
oughly; so  that  the  youth  may  be   enabled   to 


vn         THE  STUDY  OF  ZOOLOGY        225 

make  his  life  that  which  it  ought  to  be,  a  con- 
tinual progress  in  learning  and  in  wisdom. 

But,  in  addition,  primary  education  endeavours 
to  fit  a  boy  out  with  a  certain  equipment  of 
positive  knowledge.  He  is  taught  the  great  laws 
of  morality;  the  religion  of  his  sect;  so  much 
history  and  geography  as  wiU  tell  him  where  the 
great  countries  of  the  world  are,  what  they  are, 
and  how  they  have  become  what  they  are. 

Without  doubt  all  these  are  most  fitting  and 
excellent  things  to  teach  a  boy ;  I  should  be  very 
sorry  to  omit  any  of  them  from  any  scheme  of 
primary  intellectual  education.  The  system  is 
excellent,  so  far  as  it  goes. 

But  if  I  regard  it  closely,  a  curious  reflection 
arises.  I  suppose  that,  fifteen  hundred  years  ago, 
the  child  of  any  well-to-do  Roman  citizen  was 
taught  just  these  same  things ;  reading  and  writing 
in  his  own,  and,  perhaps,  the  Greek  tongue ;  the 
elements  of  mathematics  ;  and  the  religion,  moral- 
ity, history,  and  geography  current  in  his  time. 
Furthermore,  I  do  not  think  I  err  in  affirming, 
that,  if  such  a  Christian  Roman  boy,  who  had 
finished  his  education,  could  be  transplanted  into 
one  of  our  public  schools,  and  pass  through  its 
course  of  instruction,  he  would  not  meet  with  a 
single  unfamiliar  line  of  thought ;  amidst  all  the 
new  facts  he  would  have  to  learn,  not  one  would 
suggest  a  different  mode  of  regarding  the  universe 
from  that  current  in  his  own  tima 

201 


226  THE   STUDY   OF  ZOOLOGY  vii 

And  yet  surely  there  is  some  great  difterence 
between  the  civihsation  of  the  fourth  century  and 
that  of  the  nineteenth,  and  still  more  between  the 
intellectual  habits  and  tone  of  thought  of  that 
day  and  this  ? 

And  what  has  made  this  difference  ?  I  answer 
fearlessly — The  prodigious  development  of  physi- 
cal science  within  the  last  two  centuries. 

Modern  civilisation  rests  upon  physical  science  ; 
take  away  her  gifts  to  our  own  country,  and  our 
position  among  the  leading  nations  of  the  world 
is  gone  to-morrow;  for  it  is  physical  science  only 
that  makes  intelligence  and  moral  energy  stronger 
than  brute  force. 

The  whole  of  modem  thought  is  steeped  in 
science;  it  has  made  its  way  into  the  works  of 
our  best  poets,  and  even  the  mere  man  of  letters, 
who  affects  to  ignore  and  despise  science,  is  un- 
consciously impregnated  with  her  spirit,  and  in- 
debted for  his  best  products  to  her  methods.  I 
beheve  that  the  greatest  intellectual  revolution 
mankind  has  yet  seen  is  now  slowly  taking  place 
by  her  agency.  She  is  teaching  the  world  that 
the  ultimate  court  of  appeal  is  observation  and 
experiment,  and  not  authority ;  she  is  teaching  it 
to  estimate  the  value  of  evidence  ;  she  is  creating 
a  firm  and  hving  faith  in  the  existence  of  immut- 
able moral  and  physical  laws,  perfect  obedience  to 
which  is  the  highest  possible  aim  of  an  intelligent 
beincr. 


VII 


THE   STUDY   OF  ZOOLOGY  227 


But  of  all  this  your  old  stereot}^ed  system  of 
education  takes  no  note.  Physical  science,  its 
methods,  its  problems,  and  its  difficulties,  will 
meet  the  poorest  boy  at  every  turn,  and  yet  we 
educate  him  in  such  a  manner  that  he  shall  enter 
the  world  as  ignorant  of  the  existence  of  the 
methods  and  facts  of  science  as  the  day  he  was 
born.  The  modern  world  is  full  of  artillery ;  and 
we  turn  out  our  children  to  do  battle  in  it, 
equipped  with  the  shield  and  sword  of  an  ancient 
gladiator. 

Posterity  will  cry  shame  on  us  if  we  do  not 
remedy  this  deplorable  state  of  things.  Nay,  if 
we  live  twenty  years  longer,  our  own  consciences 
will  cry  shame  on  us. 

It  is  my  firm  conviction  that  the  only  way  to 
remedy  it  is  to  make  the  elements  of  physical 
science  an  integral  part  of  primary  education.  I 
have  endeavoured  to  show  you  how  that  may  be 
done  for  that  branch  of  science  which  it  is  my 
business  to  pursue;  and  I  can  but  add,  that  I 
should  look  upon  the  day  when  every  schoolmaster 
throughout  this  land  was  a  centre  of  genuine, 
however  rudimentary,  scientific  knowledge,  as  an 
epoch  in  the  history  of  the  country. 

But  let  me  entreat  you  to  remember  my  last 
words.  Addressing  myself  to  you,  as  teachers,  I 
would  say,  mere  book  learning  in  physical  science 
is  a  sham  and  a  delusion — what  you  teach,  unless 
you  wish  to  be  impostors,  that   you    must   first 


228  THE   STUDY   OF   ZOOLOGY  vn 


know;  and  real  knowledge  in  science  means 
personal  acquaintance  with  the  facts,  be  they 
few  or  many.^ 

^  It  has  "been  suggested  to  me  that  these  words  may  be  taken 
to  imply  a  discouragement  on  my  part  of  any  sort  of  scientific 
instruction  which  does  not  give  an  acquaintance  with  the  facts 
at  first  hand.  But  this  is  not  my  meaning.  The  ideal  of 
scientific  teaching  is,  no  doubt,  a  system  by  which  the  scholar 
sees  every  fact  for  himself,  and  the  teacher  supplies  only  the 
explanations.  Circumstances,  however,  do  not  often  allow  of 
the  attainment  of  that  ideal,  and  we  must  put  up  with  the 
next  best  system — one  in  which  the  scholar  takes  a  good  deal  on 
trust  from  a  teacher,  who,  knowing  the  facts  by  his  own  know- 
ledge, can  describe  them  with  so  much  vividness  as  to  enable 
his  audience  to  form  competent  ideas  concerning  them.  The 
system  which  I  repudiate  is  that  which  allows  teachers  who 
have  not  come  into  direct  contact  with  the  leading  facts  of  a 
science  to  pass  their  second-hand  information  on.  The  scientific 
virus,  like  vaccine  lymph,  if  passed  through  too  long  a  succes- 
sion of  organisms,  will  lose  all  its  effect  in  protecting  the  young 
against  the  intellectual  epidemics  to  which  they  are  exposed. 

[The  remarks  on  p.  222  applied  to  the  Natural  History  Collec- 
tion of  the  British  Museum  in  1861.  ■  The  visitor  to  the  Natural 
History  Museum  in  1894  need  go  no  further  than  the  Great  Hall 
to  see  the  realisation  of  my  hopes  by  the  present  Director.] 


VIII 
BIOGENESIS  AND  ABIOGENESIS 

(the  presidential  address  to  the  BRITISH 

ASSOCIATION  FOR  THE  ADVANCEMENT  OF  SCIENCE 

FOR  1870) 

It  has  long  been  the  custom  for  the  newly 
installed  President  of  the  British  Association  for 
the  Advancement  of  Science  to  take  advantage  of 
the  elevation  of  the  position  in  which  the  suffrages 
of  his  colleagues  had,  for  the  time,  placed  him,  and, 
casting  his  eyes  around  the  horizon  of  the  scientific 
world,  to  report  to  them  what  could  be  seen  from 
his  watch-tower ;  in  what  directions  the  multitu- 
dinous divisions  of  the  noble  army  of  the  improvers 
of  natural  knowledge  were  marching;  what 
important  strongholds  of  the  great  enemy  of  us 
all,  ignorance,  had  been  recently  captured;  and, 
also,  with  due  impartiality,  to  mark  where  the 
advanced  posts  of  science  had  been  driven  in,  or  a 
long-continued     siege     had    made    no    progress. 


230  BIOGENESIS   AND   ABIOGENESIS  vili 

1  propose  to  endeavour  to  follow  this  ancient 
precedent,  in  a  manner  suited  to  the  limitations  of 
my  knowledge  and  of  my  capacity  I  shall  not 
presume  to  attempt  a  panoramic  survey  of  the 
world  of  science,  nor  even  to  give  a  sketch  of  what 
is  doing  in  the  one  great  province  of  biology,  with 
some  portions  of  which  my  ordinary  occupations 
render  me  familiar.  But  I  shall  endeavour  to  put 
before  you  the  history  of  the  rise  and  progress  of 
a  single  biological  doctrine;  and  I  shall  try  to 
give  some  notion  of  the  fruits,  both  intellectual 
and  practical,  which  we  owe,  directly  or  indirectly, 
to  the  working  out,  by  seven  generations  of 
patient  and  laborious  investigators,  of  the 
thought  which  arose,  more  than  two  centuries 
ago,  in  the  mind  of  a  sagacious  and  observant 
Italian  naturalist. 

It  is  a  matter  of  everyday  experience  that  it  is 
difficult  to  prevent  many  articles  of  food  from 
becoming  covered  with  mould ;  that  fruit,  sound 
enough  to  all  appearance,  often  contains  grubs  at 
the  core ;  that  meat,  left  to  itself  in  the  air,  is 
apt  to  putrefy  and  swarm  with  maggots.  Even 
ordinary  water,  if  allowed  to  stand  in  an  open 
vessel,  sooner  or  later  becomes  turbid  and  full  of 
living  matter. 

The  philosophers  of  antiquity,  interrogated  as  to 
the  cause  of  these  phenomena,  were  provided  with 
a  ready  and  a  plausible  answer.  It  did  not  enter 
their  minds  even  to  doubt  that  these  low  forms  of 


Vlir  BIOGENESIS   AND   ABIOGENESIS  231 

life  were  generated  in  the  matters  in  which  they 
made  their  appearance.  Lucretius,  who  had  drunk 
deeper  of  the  scientific  spirit  than  any  poet  of 
ancient  or  modern  times  except  Goethe,  intends  to 
speak  as  a  philosopher,  rather  than  as  a  poet,  when 
he  writes  that  "with  good  reason  the  earth  has 
gotten  the  name  of  mother,  since  all  things  are 
produced  out  of  the  earth.  And  many  living 
creatures,  even  now,  spring  out  of  the  earth,  taking 
form  by  the  rains  and  the  heat  of  the  sun."  ^  The 
axiom  of  ancient  science,  "  that  the  corruption  of 
one  thing  is  the  birth  of  another,"  had  its  popular 
embodiment  in  the  notion  that  a  seed  dies  before 
the  young  plant  springs  from  it ;  a  belief  so  wide- 
spread and  so  fixed,  that  Saint  Paul  appeals  to 
it  in  one  of  the  most  splendid  outbursts  of  his 
fervid  eloquence : — 

"  Thou  fool,  that  which  thou  sowest  is  not 
quickened,  except  it   die."^ 

The  proposition  that  life  may,  and  does,  proceed 
from  that  which  has  no  Hfe,  then,  was  held  alike 
by  the  philosophers,  the  poets,  and  the  people,  of 

'  It  is  thus  that  Mr.  Munro  renders 

"  Linqnitur,  ut  merito  maternum  nomen  adepta 
Terra  sit,  e  terra  quoniam  sunt  cuncta  creata. 
Multaque  nunc  etiam  exsistant  animalia  terris 
Imbribus  et  calido  solis  concreta  vapore." 

De  Rerum  Natura,  lib.  v.  793—796. 

But  would  not  the  meaning  of  the  last  line  be  better 
rendered  "  Developed  in  rain-wat3r  and  in  the  warm  vapours 
raised  by  the  sun  "  ?  ^  I  Corinthians  xv.  36. 


232  BIOGENESIS   AND  ABIOGENESIS  vni 

the  most  enlightened  nations,  eighteen  hundred 
years  ago ;  and  it  remained  the  accepted  doctrine 
of  learned  and  unlearned  Europe,  through  the 
Middle  Ages,  down  even  to  the  seventeenth 
century. 

It  is  commonly  counted  among  the  many  merits 
of  our  great  countryman,  Harvey,  that  he  was  the 
first  to  declare  the  opposition  of  fact  to  venerable 
authority  in  this,  as  in  other  matters ;  but  I  can 
discover  no  justification  for  this  widespread 
notion.  After  careful  search  through  the  "  Exer- 
citationes  de  Generatione,"  the  most  that  appears 
clear  to  me  is,  that  Harvey  believed  all  animals 
and  plants  to  spring  from  what  he  terms  a  "  prim- 
ordium  vegetale,"  a  phrase  which  may  nowadays  be 
rendered  "  a  vegetative  germ  " ;  and  this,  he  says, 
is  "  oviforme^'  or  "  egg-like  "  ;  not,  he  is  careful  to 
add,  that  it  necessarily  has  the  shape  of  an  egg,  but 
because  it  has  the  constitution  and  nature  of  one. 
That  this  "|9Wm(5?'<fi2t?7i  cmforrm  "  must  needs,  in 
all  cases,  proceed  from  a  living  parent  is  nowhere 
expressly  maintained  by  Harvey,  though  such  an 
opinion  may  be  thought  to  be  imphed  in  one  or  two 
passages ;  while,  on  the  other  hand,  he  does,  more 
than  once,  use  language  which  is  consistent  only 
with  a  full  belief  in  spontaneous  or  equivocal 
generation.^     In  fact,  the  main  concern  of  Harvey's 

^  See  tlie  following  passage  in  Exercitatio  I.  : — "Item  sipnnU 
nasccntia  dicuntur  ;  non  quod  ex  pntredine  oviunda  sint,  sed 
q^uod  casu,  naturae  sponte,  et  isquivGca  (ut  aiunt)  generatione,  a 


Vin  BIOGENESIS   AND   ABIOGENESIS  233 

wonderful  little  treatise  is  not  with  generation,  in 
the  physiological  sense,  at  all,  but  with  develop- 
ment ;  and  his  great  object  is  the  establishment  of 
the  doctrine  of  epigenesis. 

The  first  distinct  enunciation  of  the  h}^othesis 
that  all  living  matter  has  sprung  from  pre-existing 
living  matter,  came  from  a  contemporary,  though  a 
junior,  of  Harvey,  a  native  of  that  country,  fertile 
in  men  great  in  all  departments  of  human  activity, 
which  was  to  intellectual  Europe,  in  the  sixteenth 
and  seventeenth  centuries,  what  Germany  is  in  the 
nineteenth.  It  was  in  Italy,  and  from  Italian 
teachers,  that  Harvey  received  the  most  import- 
ant part  of  his  scientific  education.  And  it  was 
a  student  trained  in  the  same  schools,  Francesco 
Redi — a  man  of  the  widest  knowledge  and  most 
versatile  abilities,  distinguished  alike  as  scholar, 
poet,  physician,  and  naturalist — who,  just  two 
hundred  and  two  years  ago,  pubhshed  his  "  Esper- 
ienze  intorno  alia  Generazione  degl'  Insetti,"  and 
gave  to  the  world  the  idea,  the  growth  of  which  it 
is  my  purpose  to  trace.  Redi's  book  went  through 
five  editions  in  twenty  years;    and  the  extreme 

parentibns  sui  dissimilibus  proveniant."  Again,  in  Dc  Uteri 
Mcmbrmiis :—'' In  cunctorum  viventium  generatione  (sicut 
diximus)  hoc  solenne  est,  ut  ortum  ducunt  a  primordio  alifjuo, 
quod  turn  materiani  turn  efficiendi  potestatem  in  se  habet : 
sitque  adeo  id,  ex  quo  et  a  quo  quicqiiid  nascitur,  ortum  suum 
ducat.  Tale  piimordium  in  animalibus  {sivc  ab  aliis gcnerantibus 
proveniant,  sivc  sponte,  aut  ex  pntredi.nc  nascentttr)  est  humor 
in  tunica  aliqua  aut  putami  ne  conchisus."  Compare  also 
what  Redi  has  to  say  respecting  Harvey's  opinions,  Ei'2)erienzef 
p.  11. 


234  BIOGENESIS   AND   ABIOGENESIS  vill 

simplicity  of  his  experiments,  and  the  clearness 
of  his  arguments,  gained  for  his  views,  and 
for  their  consequences,  almost  universal  accept- 
ance. 

Redi  did  not  trouble  himself  much  with  specu- 
lative considerations,  but  attacked  particular  cases 
of  what  was  supposed  to  be  "  spontaneous  genera- 
tion" experimentally.  Here  are  dead  animals,  or 
pieces  of  meat,  says  he ;  I  expose  them  to  the  air 
in  hot  weather,  and  in  a  few  days  they  swarm  with 
maggots.  You  tell  me  that  these  are  generated 
in  the  dead  flesh;  but  if  I  put  similar  bodies, 
while  quite  fresh,  into  a  jar,  and  tie  some  fine 
gauze  over  the  top  of  the  jar,  not  a  maggot  makes 
its  appearance,  while  the  dead  substances,  never- 
theless, putrefy  just  in  the  same  way  as  before. 
It  is  obvious,  therefore,  that  the  maggots  are  not 
generated  by  the  corruption  of  the  meat ;  and  that 
the  cause  of  their  formation  must  be  a  some- 
thing which  is  kept  away  by  gauze.  But  gauze 
will  not  keep  away  aeriform  bodies,  or  fluids. 
This  something  must,  therefore,  exist  in  the 
form  of  solid  particles  too  big  to  get  through 
the  gauze.  Nor  is  one  long  left  in  doubt 
what  these  solid  particles  are ;  for  the  blow- 
flies, attracted  by  the  odour  of  the  meat,  swarm 
round  the  vessel,  and,  urged  by  a  powerful 
but  in  this  case  misleading  instinct,  lay  eggs  out 
of  which  maggots  are  immediately  hatched,  upon 
the    gauze.      The    conclusion,  therefore,   is    un- 


VIII  BIOGENESIS  AND   ABIOGENESIS  235 

avoidable ;  the  maggots  are  not  generated  by  the 
meat,  but  the  eggs  which  give  rise  to  them  are 
brought  through  the  air  by  the  flies. 

These  experiments  seem  almost  childishly 
simple,  and  one  wonders  how  it  was  that  no  one 
ever  thought  of  them  before.  Simple  as  they  are, 
however,  they  are  worthy  of  the  most  careful  study, 
for  every  piece  of  experimental  work  since  done, 
in  regard  to  this  subject,  has  been  shaped  upon 
the  model  furnished  by  the  Italian  philosopher. 
As  the  results  of  his  experiments  were  the  same, 
however  varied  the  nature  of  the  materials  he 
used,  it  is  not  wonderful  that  there  arose  in  Redi's 
mind  a  presumption,  that,  in  all  such  cases  of  the 
seeming  production  of  life  from  dead  matter, 
the  real  explanation  was  the  introduction  of 
hving  germs  from  without  into  that  dead  matter.^ 

^  "  Pure  contentandomi  semprein  questa  ed  in  ciascuna  altro 
cosa,  da  eiascuno  piu  savio,  la  dove  io  difettuosamente  ])arlassi, 
e.sser  corretto  ;  nontaceio,  cheper  molteosservazioni  molti  volti 
da  nie  fatte,  mi  sento  inclinato  a  credere  che  la  terra,  da  quelle 
prime  piaute,  e  da  quel  primi  aniiuali  in  poi,  che  ella  nei  primi 
giorni  del  mondo  produsse  per  comandemento  del  sovrano  ed 
omnipotente  Fattore,  non  abbiamaipiii  prodotto  da  se  medesima 
lie  erba  ne  albero,  ne  animale  alcuno  porfetto  o  imperfetto  che 
ei  se  fosse  ;  e  che  tutto  quello,  che  ne'  tempi  trapassati  e  nato 
e  che  ora  nascere  in  lei,  o  da  lei  veggiamo,  venga  tutto  dalla 
semenza  reale  e  vera  delle  piante,  e  degli  animali  stessi,  i  quali 
col  mezzo  del  proprio  seme  la  loro  spezie  conservano.  E  se  hene 
tutto  giorno  scorghiamo  da'  cadaveri  degli  animali,  e  da  tutte 
quante  le  maniere  dell'  erbe,  e  de'  fiori,  e  dei  frutti  imputriditi, 
e  corrotti  nascere  vermi  infiniti — 

'  Nonne  vides  qusecunque  mora,  fluidoque  calore 

Corpora  tabescunt  in  parva  animalia  verti ' — 

Io  mi  sento,  dico,  inclinato,  a  credere  che  tutti  quel  vermi  si 


236  BIOGENESIS   AND   ABIOGENESIS  vm 

And  thus  the  hypothesis  that  living  matter  always 
arises  by  the  agency  of  pre-existing  Hving  matter, 
took  definite  shape ;  and  had,  henceforward,  a 
right  to  be  considered  and  a  claim  to  be  refuted,  in 
each  particular  case,  before  the  production  of  Hving 
matter  in  any  other  way  could  be  admitted  by 
careful  reasoners.  It  will  be  necessary  for  me  to 
refer  to  this  h}^othesis  so  frequently,  that,  to  save 
circumlocution,  I  shall  call  it  the  hypothesis  of 
Biogenesis ;  and  I  shall  term  the  contrary  doctrine 
— that  living  matter  may  be  produced  by  not 
living  matter — the  h}^othesis  of  Abio genesis. 

In  the  seventeenth  century,  as  I  have  said,  the 
latter  was  the  dominant  view,  sanctioned  ahke  by 
antiquity  and  by  authority;  and  it  is  interesting 
to  observe  that  Redi  did  not  escape  the  customary 
tax  upon  a  discoverer  of  having  to  defend  himself 
against  the  charge  of  impugning  the  authority  of 
the  Scriptures ;  ^  for  his  adversaries  declared  that 

generino  dal  seme  paterno  ;  e  che  le  carni,  e  T  erbe,  e  1'  altre 
cose  tutte  putrefatte,  o  putrefattibili  non  facciano  altra  parte, 
re  abbiano  altro  ufizio  nella  generazione  degl'  insetti,  se  non 
•d'apprestare  un  luogo  o  un  nido  proporzionato,  in  cui  dagli 
aniraali  nel  tempo  della  figliatura  sieno  portati,  e  partoriti  i 
vermi,  o  1'  nova  o  1'  altre  semenze  del  vermi,  i  quali  tosto  che 
nati  sono,  trovano  in  esso  nido  nn  suflBciente  alimento  abilissimo 
per  nutricarsi  :  e  se  in  queUo  non  son  portate  dalle  madri  queste 
suddette  semenze,  niente  mai,  e  replicatameute  niente,  vis'in- 
gegnevi  e  nasca." — Redi,  Espcricnzc,  pp.  14-16. 

^  "  ilolti,  e  molti  altri  aneora  vi  potrei  annoverare,  se  non 
fossi  chiamato  a  rispondere  alle  rampogne  di  alcuni,  che  brusca- 
mente  mi  rammentano  cio,  che  si  legge  nel  capitolo  qnattor- 
dicesimo  del  sacrosanto  Libro  de'  giudici.  .  .  ." — Redi,  loc.  cit, 
p.  45. 


VIII  BIOGENESIS   AND   ABIOGENESIS  237 

the  generation  of  bees  from  the  carcase  of  a  dead 
lion  is  affirmed,  in  the  Book  of  Judges,  to  have 
been  the  origin  of  the  famous  riddle  with  which 
Samson  perplexed  the  Philistines  : — 

"  Out  of  the  eater  came  fortli  meat, 
And  out  of  the  strong  came  forth  sweetness." 

Against  all  odds,  however,  Redi,  strong  with 
the  strength  of  demonstrable  fact,  did  splendid 
battle  for  Biogenesis;  but  it  is  remarkable  that 
he  held  the  doctrine  in  a  sense  which,  if  he  had 
lived  in  these  times,  would  have  infallibly  caused 
him  to  be  classed  among  the  defenders  of  "  spon- 
taneous generation."  "  Omne  vivum  ex  vivo," 
*'  no  life  without  antecedent  life,"  aphoristically 
sums  up  Redi's  doctrine ;  but  he  went  no  further. 
It  is  most  remarkable  evidence  of  the  philosophic 
caution  and  impartiality  of  his  mind,  that  although 
he  had  speculatively  anticipated  the  manner  in 
which  grubs  really  are  deposited  in  jfruits  and  in 
the  galls  of  plants,  he  deliberately  admits  that  the 
evidence  is  insufficient  to  bear  him  out;  and  he 
therefore  prefers  the  supposition  that  they  are 
generated  by  a  modification  of  the  living  substance 
of  the  plants  themselves.  Indeed,  he  regards 
these  vegetable  growths  as  organs,  by  means  of 
which  the  plant  gives  rise  to  an  animal,  and  looks 
upon  this  production  of  specific  animals  as  the 
final  cause  of  the  gaUs  and  of,  at  any  rate,  some 
fruits.    And  he  proposes  to  explain  the  occurrence 


238  BIOGENESIS   AND   ABIOGENESIS  vill 

of  parasites  within  the  animal  body  in  the  same 
way.^ 

1  The  passage  {Espericnze,  p.  129)  is  worth  quoting  in  full  :— 
"  Se  dovessi  palesarvi  il  mio  sentimento  crederei  che  i  frutti, 
i  logumi,  gli  alberi  e  le  foglie,  in  due  nianiere  inverminassero. 
Una,  perche  venendo  i  bachi  ])er  di  fuora,  e  cercando  1'  alimento, 
col  rodere  ci  aprono  la  strada,  ed  arrivano  alia  \>i\x  interna 
midolla  de'  frutti  e  de'  legni.  L'altra  nianiera  si  e,  che  io  ptr 
me  stimerei,  che  non  fosse  gran  fatto  disdicevole  il  credere,  che 
queir  anima  o  quella  virt'i  la  quale  genera  i  fiori  ed  i  frutti 
nelle  piante  viventi,  sia  quella  stessa  che  generi  ancora  i  bachi 
di  esse  piante.  E  chi  sa  forse,  che  molti  frutti  degli  alberi  non 
sieno  prodotti,  non  per  un  fine  primario  e  principale,  ma  bensi 
per  un  uffizio  secondario  e  servile,  destinato  alia  generazione  di 
que'  vermi,  servendo  a  lore  in  vece  di  matrice,  in  cui  dimorino 
un  prefisso  e  determiuato  tempo  ;  11  quale  arrivato  escan  fuora  a 
godere  il  sole. 

**  Io  m'  immagino,  che  questo  mio  pensiero  non  viparra  total- 
mente  un  paradosso  ;  mentre  farete  riflessione  a  quelle  tante 
sorte  di  galle,  di  gallozzole,  di  coccole,  di  ricci,  di  calici,  di 
cornetti  ed  i  lappole,  che  son  produtte  dalle  quercel,  dalle  farnie, 
da'  cerri,  da'  su.heri,  da'  lecci  e  da  altri  simili  alberi  da  ghianda  ; 
imperciocche  in  quelle  gallozzole,  e  jtarticolarmente  nelle  piii 
grosse,  che  si  chiamano  coronati,  ne"  ricci  capelluti,  che  ciuttbli 
da'  nostri  contadini  son  detti ;  nei  ricci  legnosi  del  cerro,  iie' 
ricci  stellati  della  querela,  nelle  galluzze  della  foglia  del  leccio  si 
vede  eviilentissimameute,  che  la  prima  e  principale  intenzione 
della  natura  e  formare  dentro  di  quelle  un  animale  volante  ; 
vedendosi  nel  centro  della  gallozzola  un  novo,  che  col  crescere  e  col 
maturarsi  di  essa  gallozzola  va  crescendo  e  maturando  anch' 
egli,  e  cresce  altresi  a  suo  tempo  quel  vermc,  chn  nell'  novo  si 
racchiude  ;  il  qual  verme,  quando  la  gallozzola  e  tinita  di  matu- 
rare  e  che  e  venuto  il  termine  destinato  al  suo  nascimento, 
diventa,  di  verme  che  era,  una  mosca.  .  .  .  Io  vi  confesso  in- 
genuamente,  che  prima  d'aver  fatte  queste  mie  esperienze  intorno 
alia  generazione  degl'  insetti  mi  dava  a  credere,  o  per  dir  meglio 
sospettava,  che  forse  la  gallozzola  nascesse,  perche  arrivando  la 
mosca  nel  tempo  della  primavera,  e  facendo  una  }>iccolissima 
fessura  ne'  rami  piu  teneri  dt-lla  querela,  in  quella  fessura  nas- 
condesse  uno  de  suol  semi,  11  quale  fosse  cagione  che  sbocciasse 
fuora  la  gallozzola  ;  e  che  mai  non  si  vedessero  galle  o  gallozzole 
o  ricci  o  cornetti  o  calici  o  coccole,  se  non  in  que'  rami,  ne'  quali 
le  mosche  avessero  depositate  le  lore  semenze  ;  e  ml  dava  ad 
intendere,  che  le  gallozzole  fossero  una  malattla  cagiouata  nelle 


VIII  BIOGENESIS   AND   ABIOGENESIS  239 

It  is  of  great  importance  to  apprehend  Redi's 
position  rightly ;  for  the  hnes  of  thought  he  laid 
down  for  us  are  those  upon  which  naturalists  have 
been  working  ever  since.  Clearly,  he  held  Bio- 
genesis as  against  Abio genesis ;  and  I  shall  imme- 
diately proceed,  in  the  first  place,  to  inquire  how 
far  subsequent  investigation  has  borne  him  out  in 
so  doing. 

But  Redi  also  thought  that  there  were  two 
modes  of  Biogenesis.  By  the  one  method,  which 
is  that  of  common  and  ordinary  occurrence,  the 
living  parent  gives  rise  to  offspring  which  passes 
through  the  same  cycle  of  changes  as  itself — like 
gives  rise  to  like ;  and  this  has  been  termed 
Hcmogenesis.  By  the  other  mode,  the  living 
parent  was  supposed  to  give  rise  to  offspring 
which  passed  through  a  totally  different  series  of 
states  from  those  exhibited  by  the  parent,  and 
did  not  return  into  the  cycle  of  the  parent ;  this 
is  what  ought  to  be  called  Hetero genesis,  the  off- 
spring being  altogether,  and  permanently,  unlike 
the  parent.  The  term  Heterogenesis,  however, 
has  unfortunately  been  used  in  a  different  sense, 
and  M.  Milne-Edwards  has  therefore  substituted 
for  it  Xenogenesis,  which  means  the  generation  of 
something  foreign.  After  discussing  Redi's  hypo- 
thesis of  universal   Biogenesis,  then,  I  shall  go 

qiierce  dalle  punture  delle  mosche,  in  quella  giusa  stessa  che 
dalle  puuture  d'  altri  animaletti  simiglievoli  veggiamo  crescere 
de'  tumori  ue'  coi-pi  degli  animali." 


240  BIOGENESIS   AND   ABIOGENESIS  vill 

on  to  ask  how  far  the  growth  of  science  justifies 
his  other  hypothesis  of  Xenogenesis. 

The  progress  of  the  hypothesis  of  Biogenesis 
was  triumphant  and  unchecked  for  nearly  a 
century.  The  apphcation  of  the  microscope  to 
anatomy  in  the  hands  of  Grew,  Leeuwenhoek, 
Swammerdam,  Lyonnet,  Vallisnieri,  Reaumur,  and 
other  illustrious  investigators  of  nature  of  that 
day,  disjDlayed  such  a  complexity  of  organisation 
in  the  lowest  and  minutest  forms,  and  everywhere 
revealed  such  a  prodigahty  of  provision  for  their 
multiplication  by  germs  of  one  sort  or  another, 
that  the  hypothesis  of  Ahiogenesis  began  to 
appear  not  only  untrue,  but  absurd ;  and,  in  the 
middle  of  the  eighteenth  century,  when  Needham 
and  Buffon  took  up  the  question,  it  was  almost 
universally  discredited.^ 

But  the  skill  of  the  microscope  makers  of  the 
eighteenth  century  soon  reached  its  limit.  A 
microscope  magnifying  400  diameters  was  a  chef 
d'ceuvre  of  the  opticians  of  that  day;  and,  at  the 
same  time,  by  no  means  trustworthy.  But  a 
magnifying  power  of  400  diameters,  even  when 

^  Needham,  writing  in  1750,  says  : — 

"  Les  naturalistes  modernes  s'accordent  nnaninenient  aetablir, 
comme  nne  verite  certaine,  que  toute  plante  vient  de  sa  semence 
specihque,  tout  animal  d'un  ceuf  ou  de  quelque  chose  d'analogue 
pieexistant  dans  la  plante,  ou  dans  Tanimal  de  meme  espece  qui 
I'a  produit." — Nouvdles  Observations,  p.  169. 

"Les  naturalistes  ont  generalemente  era  que  les  animaux 
microscopiques  etaient  engendres  par  des  oeufs  transportes  dans 
I'air,  ou  deposes  dans  des  eaux  donnantes  par  des  insectes 
volans," — Ihid.  p.  176, 


VIII  BIOGENESIS   AND   ABIOGENESIS  241 

definition  ]:eaclies  the  exquisite  perfection  of  our 
modem  achromatic  lenses,  hardly  suffices  for  the 
mere  discernment  of  the  smallest  forms  of  life. 
A  speck,  only  gV^^  ^^  ^^  ii^ch  in  diameter,  has,  at 
ten  inches  from  the  eye,  the  same  apparent  size 
as  an  object  looooth  of  an  inch  in  diameter, 
when  magnified  400  times;  but  forms  of  living 
matter  abound,  the  diameter  of  which  is  not  more 
than  xo-o-cro-^^  of  an  inch.  A  filtered  infusion  of 
hay,  allowed  to  stand  for  two  days,  will  swarm 
with  living  things  among  which,  any  which 
reaches  the  diameter  of  a  human  red  blood- 
corpuscle,  or  about  3^0*^^  ^f  ^n  inch,  is  a  giant. 
It  is  only  by  bearing  these  facts  in  mind,  that  we 
can  deal  fairly  with  the  remarkable  statements 
and  speculations  put  forward  by  Bufifon  and 
Needham  in  the  middle  of  the  eig^hteenth 
century. 

When  a  portion  of  any  animal  or  vegetable 
body  is  infused  in  water,  it  gradually  softens  and 
disintegrates;  and,  as  it  does  so,  the  water  is 
found  to  swarm  with  minute  active  creatures,  the 
so-called  Infusorial  Animalcules,  none  of  which 
can  be  seen,  except  by  the  aid  of  the  microscope  ; 
while  a  large  proportion  belong  to  the  category  of 
smallest  things  of  which  I  have  spoken,  and 
which  must  have  looked  like  mere  dots  and  lines 
under  the  ordinary  microscopes  of  the  eighteenth 
century. 

Led  by  various  theoretical  considerations  which 
202 


242  BIOGENESIS  AND   ABIOGENESIS  viil 

I  cannot  now  discuss,  but  which  looked  promising 
enouofh  in  the  lio-hts  of  their  time,  Buffon  and 
Needham  doubted  the  applicabihty  of  Redi's 
hypothesis  to  the  infusorial  animalcules,  and 
Needham  very  properly  endeavoured  to  put  the 
question  to  an  experimental  test.  He  said  to 
himself,  If  these  infusorial  animalcules  come  from 
germs,  their  germs  must  exist  either  in  the  sub- 
stance infused,  or  in  the  water  with  which  the 
infusion  is  made,  or  in  the  superjacent  air.  Now 
the  vitality  of  all  germs  is  destroyed  by  heat. 
Therefore,  if  I  boil  the  infusion,  cork  it  up  care- 
fully, cementing  the  cork  over  with  mastic,  and 
then  heat  the  whole  vessel  by  heaping  hot  ashes 
over  it,  I  must  needs  kill  whatever  germs  are 
present.  Consequently,  if  Redi's  hypothesis  hold 
good,  when  the  infusion  is  taken  away  and  allowed 
to  cool,  no  animalcules  ought  to  be  developed  in 
it ;  whereas,  if  the  animalcules  are  not  dependent 
on  pre-existing  germs,  but  are  generated  from  the 
infused  substance,  they  ought,  by  and  by,  to  make 
their  appearance.  Needham  found  that,  under 
the  circumstances  in  which  he  made  his  experi- 
ments, animalcules  always  did  arise  in  the 
infusions,  when  a  sufficient  time  had  elapsed  to 
allow  for  their  development. 

In  much  of  his  work  Needham  was  associated 
with  BufiPon,  and  the  results  of  their  experiments 
fitted  in  admirably  with  the  great  French  natural- 
ist's hypothesis  of  "  organic  molecules,"  according 


VIII  BIOGENESIS   AND   ABIOGENESIS  243 

to  which,  Kfe  is  the  indefeasible  property  of  certain 
indestructible  molecules  of  matter,  which  exist  in 
all  livinor  thino^s,  and  have  inherent  activities 
by  which  they  are  distinguished  from  not  hving 
matter.  Each  individual  living  organism  is 
formed  by  their  temporary  combination.  They 
stand  to  it  in  the  relation  of  the  particles  of 
water  to  a  cascade,  or  a  whirlpool ;  or  to  a  mould, 
into  which  the  water  is  poured.  The  form  of  the 
organism  is  thus  determined  by  the  reaction 
between  external  conditions  and  the  inherent 
activities  of  the  organic  molecules  of  which  it  is 
composed;  and,  as  the  stoppage  of  a  whirlpool 
destroys  nothing  but  a  form,  and  leaves  the 
molecules  of  the  water,  with  all  their  inherent 
activities  intact,  so  what  we  call  the  death  and 
putrefaction  of  an  animal,  or  of  a  plant,  is  merely 
the  breaking  up  of  the  form,  or  manner  of  asso- 
ciation, of  its  constituent  organic  molecules,  which 
are  then  set  free  as  infusorial  animalcules. 

It  will  be  perceived  that  this  doctrine  is  by  no 
means  identical  with  Abiogenesis,  with  which  it  is 
often  confounded.  On  this  h\^othesis,  a  piece  of 
beef,  or  a  handful  of  hay,  is  dead  only  in  a  limited 
sense.  The  beef  is  dead  ox,  and  the  hay  is  dead 
grass ;  but  the  "  organic  molecules  "  of  the  beef  or 
the  hay  are  not  dead,  but  are  ready  to  manifest 
their  vitality  as  soon  as  the  bovine  or  herbaceous 
shrouds  in  which  they  are  imprisoned  are  rent  by 
the  macerating  action  of  water.     The  h3rpothesi3 


244  BIOGENESIS  AND  ABIOGENESIS  \m 

therefore  must  be  classified  under  Xenogenesis, 
rather  than  under  Abiogenesis.  Such  as  it  was,  I 
think  it  will  appear,  to  those  who  will  be  just 
enough  to  remember  that  it  was  propounded 
before  the  birth  of  modern  chemistry,  and  of  the 
modern  optical  arts,  to  be  a  most  ingenious  and 
suggestive  speculation. 

But  the  great  tragedy  of  Science — the  slaying  of 
a  beautiful  hypothesis  by  an  ugly  fact — which  is  so 
constantly  being  enacted  under  the  eyes  of  philo- 
sophers, was  played,  almost  immediately,  for  the 
benefit  of  Buff  on  and  Needham. 

Once  more,  an  Italian,  the  Abbt^  Spallanzani,  a 
worthy  successor  and  representative  of  Redi  in  his 
acuteness,  his  ingenuity,  and  his  learning,  sub- 
jected the  experiments  and  the  conclusions  of 
Needham  to  a  searching  criticism.  It  might  be 
true  that  Needham's  experiments  yielded  results 
such  as  he  had  described,  but  did  they  bear  out 
his  arguments  ?  Was  it  not  possible,  in  the  first 
place,  he  had  not  completely  excluded  the  air  by  his 
corks  and  mastic  ?  And  was  it  not  possible,  in  the 
second  place,  that  he  had  not  sufficiently  heated 
his  infusions  and  the  superjacent  air  ?  Spallan- 
zani joined  issue  with  the  English  naturalist  on 
both  these  pleas,  and  he  showed  that  if,  in  the  first 
place,  the  glass  vessels  in  which  the  infusions  were 
contained  were  hermetically  sealed  by  fusing  their 
necks,  and  if,  in  the  second  place,  they  were  ex- 
posed to   the   temperature   of  boiling  water  for 


vm  BIOGENESIS   AND   ABIOGENESIS  245 

three-quarters  of  an  hour/  no  animalcules  ever 
made  their  appearance  within  them.  It  must  be 
admitted  that  the  experiments  and  arguments  of 
Spallanzani  furnish  a  complete  and  a  crushing 
reply  to  those  of  Needham.  But  we  all  too  often 
forget  that  it  is  one  thing  to  refute  a  proposition, 
and  another  to  prove  the  truth  of  a  doctrine  which, 
imphcitly  or  explicitly,  contradicts  that  propo- 
sition ;  and  the  advance  of  science  soon  showed 
that  though  Needham  might  be  quite  wrong,  it 
did  not  follow  that  Spallanzani  was  quite  right. 

Modern  Chemistry,  the  birth  of  the  latter  half 
of  the  eighteenth  century,  grew  apace,  and  soon 
found  herself  face  to  face  with  the  great  problems 
which  biology  had  vainly  tried  to  attack  without 
her  help.  The  discovery  of  oxygen  led  to  the  lay- 
ing of  the  foundations  of  a  scientific  theory  of 
respiration,  and  to  an  examination  of  the  marvel- 
lous interactions  of  organic  substances  with 
oxygen.  The  presence  of  free  oxygen  appeared  to 
be  one  of  the  conditions  of  the  existence  of  life, 
and  of  those  singular  changes  in  organic  matters 
which  are  known  as  fermentation  and  putrefaction. 
The  question  of  the  generation  of  the  infusory 
animalcules  thus  passed  into  a  new  phase.  For 
what  might  not  have  happened  to  the  organic 
matter  of  the  infusions,  or  to  the  oxygen  of  the 
air,  in  Spallanzani's  experiments  ?  What  security 
was  there  that  the  development  of  life  which  ought 

*  See  Spallanzani,  Opere,  vi.  pp.  42  and  51. 


246  BIOGENESIS   AND   ABIOGENESIS  viil 

to  have  taken  place  had  not  been  checked  or  pre- 
vented by  these  changes  ? 

The  battle  had  to  be  fought  again.  It  was  need- 
ful to  repeat  the  experiments  under  conditions 
which  would  make  sure  that  neither  the  oxygen  of 
the  air,  nor  the  composition  of  the  organic  matter, 
was  altered  in  such  a  manner  as  to  interfere  with 
the  existence  of  life. 

Schulze  and  Schwann  took  up  the  question  from 
this  point  of  view  in  1836  and  1837.  The  passage 
of  air  through  red-hot  glass  tubes,  or  through 
strong  sulphuric  acid,  does  not  alter  the  propor- 
tion of  its  oxygen,  while  it  must  needs  arrest,  or 
destroy,  any  organic  matter  which  may  be  con- 
tained in  the  air.  These  experimenters,  therefore, 
contrived  arrangements  by  which  the  only  air 
which  should  come  into  contact  with  a  boiled  in- 
fusion should  be  such  as  had  either  passed  through 
red-hot  tubes  or  through  strong  sulphuric  acid. 
The  result  which  they  obtained  was  that  an  in- 
fusion so  treated  developed  no  living  things,  while, 
if  the  same  infusion  was  afterwards  exposed  to  the 
air,  such  things  appeared  rapidly  and  abundantly. 
The  accuracy  of  these  experiments  has  been 
alternately  denied  and  affirmed.  Supposing  them 
to  be  accepted,  however,  all  that  they  really  proved 
was  that  the  treatment  to  which  the  air  was 
subjected  destroyed  something  that  was  essential 
to  the  development  of  life  in  the  infusion.  This 
"  something  "  might  be  gaseous,  fluid,  or   solid  ; 


VIII  BIOGENESIS   AND   ABIOGENESIS  247 

that  it  consisted  of  germs  remained  only  an  hypo- 
thesis of  greater  or  less  probability. 

Contemporaneously  with  these  investigations  a 
remarkable  discovery  was  made  by  Cagniard  de  la 
Tour.  He  found  that  common  yeast  is  com- 
posed of  a  vast  accumulation  of  minute  plants. 
The  fermentation  of  must,  or  of  wort,  in  the 
fabrication  of  wine  and  of  beer,  is  always  accom- 
panied by  the  rapid  growth  and  multiplication  of 
these  Torulce.  Thus,  fermentation,  in  so  far  as  it 
was  accompanied  by  the  development  of  micro- 
scopical organisms  in  enormous  numbers,  became 
assimilated  to  the  decomposition  of  an  infusion  of 
ordinary  animal  or  vegetable  matter ;  and  it  was 
an  obvious  suggestion  that  the  organisms  were,  in 
some  way  or  other,  the  causes  both  of  fermentation 
and  of  putrefaction.  The  chemists,  with  Berzelius 
and  Liebig  at  their  head,  at  first  laughed  this  idea 
to  scorn ;  but  in  1843,  a  man  then  very  young, 
who  has  since  performed  the  unexampled  feat  of 
attaining  to  high  eminence  alike  in  Mathematics, 
Physics,  and  Physiology — I  speak  of  the  illustrious 
Helmholtz — reduced  the  matter  to  the  test  of 
experiment  by  a  method  alike  elegant  and  con- 
clusive. Helmholtz  separated  a  putrefying  or  a 
fermenting  liquid  from  one  which  was  simply 
putrescible  or  fermentable  by  a  membrane  Avhich 
allowed  the  fluids  to  pass  through  and  become 
intermixed,  but  stopped  the  passage  of  solids. 
The  result  was,  that  while  the  putrescible  or  the 


248  BIOGENESIS   AND  ABIOGENESIS  VIII 

fermentable  liquids  became  impregnated  with  the 
results  of  the  putrescence  or  fermentation  which 
was  sfoins:  on  on  the  other  side  of  the  membrane, 
they  neither  putrefied  (in  the  ordinary  way)  nor 
fermented  ;  nor  were  any  of  the  organisms  which 
abounded  in  the  fermenting  or  putrefying  liquid 
generated  in  them.  Therefore  the  cause  of  the 
development  of  these  organisms  must  lie  in  some- 
thing which  cannot  pass  through  membranes  ;  and 
as  Helmholtz's  investigations  were  long  antecedent 
to  Graham's  researches  upon  colloids,  his  natural 
conclusion  was  that  the  agent  thus  intercepted 
must  be  a  solid  material.  In  point  of  fact. 
Helmholtz's  experiments  narrowed  the  issue  to 
this  :  that  which  excites  fermentation  and  putre- 
faction, and  at  the  same  time  gives  rise  to  living 
forms  in  a  fermentable  or  putrescible  fluid,  is  not 
a  ofas  and  is  not  a  diffusible  fluid  ;  therefore  it  is 
either  a  colloid,  or  it  is  matter  divided  into  very 
minute  solid  particles. 

The  researches  of  Schroeder  and  Dusch  in  1854, 
and  of  Schroeder  alone,  in  1859,  cleared  up  this 
point  by  experiments  which  are  simply  refine- 
ments upon  those  of  Redi.  A  lump  of  cotton-wool 
is,  physically  speaking,  a  pile  of  many  thicknesses 
of  a  very  fine  gauze,  the  fineness  of  the  meshes  of 
which  depends  upon  the  closeness  of  the  compres- 
sion of  the  wool.  Now,  Schroeder  and  'Dusch 
found,  that,  in  the  case  of  all  the  putrefiable 
materials  which  they  used  (except  milk  and  yolk 


VIII  BIOGENESIS   AND   ABIOGENESIS  249 

of  egg),  an  infusion  boiled,  and  then  allowed  to 
come  into  contact  with  no  air  but  such  as  had 
been  filtered  through  cotton-wool,  neither  putre- 
fied, nor  fermented,  nor  developed  Hving  forms. 
It  is  hard  to  imagine  what  the  fine  sieve  formed 
by  the  cotton-wool  could  have  stopped  except 
minute  soHd  particles.  Still  the  evidence  was 
incomplete  until  it  had  been  positively  sho^^Ti, 
first,  that  ordinary  air  does  contain  such  particles  ; 
and,  secondly,  that  filtration  through  cotton-wool 
arrests  these  particles  and  allows  only  physically 
pure  air  to  pass.  This  demonstration  has  been 
furnished  within  the  last  year  by  the  remarkable 
experiments  of  Professor  Tyndall.  It  has  been  a 
common  objection  of  Abiogenists  that,  if  the 
doctrine  of  Biogeny  is  true,  the  air  must  be  thick 
with  germs  ;  and  they  regard  this  as  the  height  of 
absurdity.  But  nature  occasionally  is  exceedingly 
unreasonable,  and  Professor  TjTidall  has  proved 
that  this  particular  absurdity  may  nevertheless  be 
a  reality.  He  has  demonstrated  that  ordinary  air 
is  no  better  than  a  sort  of  stirabout  of  excessively 
minute  solid  particles;  that  these  particles  are 
almost  wholly  destructible  by  heat ;  and  that  they 
are  strained  off,  and  the  air  rendered  optically 
pure,  by  its  being  passed  through  cotton -wool 

It  remains  yet  in  the  order  of  logic,  though 
not  of  history,  to  show  that  among  these  solid 
destructible  particles,  there  really  do  exist  germs 
capable  of  giving  rise  to  the  development  of  living 


250  BIOGENESIS   AND   ABIOGENESIS  viii 

forms  in  suitable  menstrua.  This  piece  of  work  was 
done  by  M.  Pasteur  in  those  beautiful  researches 
which  will  ever  render  his  name  famous;  and 
which,  in  spite  of  all  attacks  upon  them,  appear 
to  me  now,  as  they  did  seven  years  ago,^  to  be 
models  of  accurate  experimentation  and  logical 
reasoning.  He  strained  air  through  cotton-wool, 
and  found,  as  Schroeder  and  Dusch  had  done,  that 
it  contained  nothing  competent  to  give  rise  to  the 
development  of  life  in  fluids  highly  fitted  for  that 
purpose.  But  the  important  further  links  in  the 
chain  of  evidence  added  by  Pasteur  are  three.  In 
the  first  place  he  subjected  to  microscopic  exam- 
ination the  cotton-wool  which  had  served  as 
strainer,  and  found  that  sundry  bodies  clearly 
recognisable  as  germs,  were  among  the  solid 
particles  strained  off.  Secondly,  he  proved  that 
these  germs  were  competent  to  give  rise  to  living 
forms  by  simply  sowing  them  in  a  solution  fitted 
for  their  development.  And,  thirdly,  he  showed 
that  the  incapacity  of  air  strained  through  cotton- 
wool to  give  rise  to  life,  was  not  due  to  any  occult 
change  effected  in  the  constituents  of  the  air  by 
the  wool,  by  proving  that  the  cotton-wool  might 
be  dispensed  with  altogether,  and  perfectly  free 
access  left  between  the  exterior  air  and  that  in  the 
experimental  flask.  If  the  neck  of  the  flask  is 
dra^vn  out  into  a  tube  and  bent  downwards ;  and 

'  Lectures  to  Working  Men  on  the  Caicses  of  the  Phenomena  of 
Organic  Nature^  1863.    (See  Vol.  II.  of  these  Essays.) 


VIII  BIOGENESIS   AND   ABIOGENESIS  251 

if,  after  the  contained  fluid  has  been  carefully 
boiled,  the  tube  is  heated  sufficiently  to  destroy 
any  germs  which  may  be  present  in  the  air  which 
enters  as  the  fluid  cools,  the  apparatus  may  be 
left  to  itself  for  any  time  and  no  life  will  appear 
in  the  fluid.  The  reason  is  plain.  Although  there 
is  free  communication  between  the  atmosphere 
laden  with  germs  and  the  germless  air  in  the  flask, 
contact  between  the  two  takes  place  only  in  the 
tube ;  and  as  the  germs  cannot  fall  upwards,  and 
there  are  no  currents,  they  never  reach  the  interior 
of  the  flask.  But  if  the  tube  be  broken  short  off 
where  it  proceeds  from  the  flask,  and  free  access 
be  thus  given  to  germs  falling  vertically  out  of 
the  air,  the  fluid,  which  has  remained  clear  and 
desert  for  months,  becomes,  in  a  few  days,  turbid 
and  full  of  life. 

These  experiments  have  been  repeated  over  and 
over  again  by  independent  observers  with  entire 
success;  and  there  is  one  very  simple  mode  of 
seeing  the  facts  for  one's  self,  which  I  may  as  well 
describe. 

Prepare  a  solution  (much  used  by  M.  Pasteur, 
and  often  called  "  Pasteur's  solution  "  )  composed 
of  water  with  tartrate  of  ammonia,  sugar,  and 
yeast-ash  dissolved  therein.^  Divide  it  into  three 
portions  in  as  many  flasks;  boil  all  three  for  a 

^  Infusion  of  hay  treated  in  the  same  way  yields  similar 
results  ;  but  as  it  contains  organic  matter,  the  argument  wliich 
follows  cannot  be  based  upon  it. 


252  BIOGENESIS   AND   ABIOGENESIS  Tin 

quarter  of  an  hour ;  and,  while  the  steam  is  passing 
out,  stop  the  neck  of  one  with  a  large  plug  of 
cotton-wool,  so  that  this  also  may  be  thoroughly 
steamed.  Now  set  the  flasks  aside  to  cool,  and, 
when  their  contents  are  cold,  add  to  one  of  the  open 
ones  a  drop  of  filtered  infusion  of  hay  which  has 
stood  for  twenty-four  hours,  and  is  consequently 
full  of  the  active  and  excessively  minute  organisms 
known  as  Bacteria.  In  a  couple  of  days  of  ordinary 
warm  weather  the  contents  of  this  flask  will  be 
milky  from  the  enormous  multij)lication  of  Bacteria. 
The  other  flask,  open  and  exposed  to  the  air,  will, 
sooner  or  later,  become  milky  with  Bacteria,  and 
patches  of  mould  may  appear  in  it ;  while  the  liquid 
in  the  flask,  the  neck  of  which  is  plugged  with 
cotton-wool,  will  remain  clear  for  an  indefinite 
time.  I  have  sought  in  vain  for  any  explanation 
of  these  facts,  excejDt  the  obvious  one,  that  the  air 
contains  germs  competent  to  give  rise  to  Bacteria, 
such  as  those  with  which  the  first  solution  has 
been  knowingly  and  purposely  inoculated,  and  to 
the  m.OM\di-Fungi.  And  I  have  not  yet  been  able 
to  meet  with  any  advocate  of  Abiogenesis  who 
seriously  maintains  that  the  atoms  of  sugar,  tar- 
trate of  ammonia,  yeast-ash,  and  water,  under  no  in- 
fluence but  that  of  free  access  of  air  and  the  ordinary 
temperature,  re-arrange  themselves  and  give  rise 
to  the  protoplasm  of  Bacterium.  But  the  alterna- 
tive is  to  admit  that  these  Bacteria  arise  from 
germs  in  the  air ;  and  if  they  are  thus  propagated, 


VIII  BIOGENESIS   AND   ABIOGENESIS  253 

the  burden  of  proof  that  other  Kke  forms  are 
generated  in  a  different  manner,  must  rest  with 
the  assertor  of  that  proposition. 

To  sum  up  the  effect  of  this  long  chain  of 
evidence : — 

It  is  demonstrable  that  a  fluid  eminently  fit  for 
the  development  of  the  lowest  forms  of  life,  but 
which  contains  neither  germs,  nor  any  protein 
compound,  gives  rise  to  living  things  in  great 
abundance  if  it  is  exposed  to  ordinary  air ;  while 
no  such  development  takes  place,  if  the  air  with 
which  it  is  in  contact  is  mechanically  freed  from 
the  solid  particles  which  ordinarily  float  in  it,  and 
which  may  be  made  visible  by  appropriate  means 

It  is  demonstrable  that  the  great  majority  of 
these  particles  are  destructible  by  heat,  and  that 
some  of  them  are  germs,  or  living  particles,  capable 
of  giving  rise  to  the  same  forms  of  life  as  those 
which  appear  when  the  fluid  is  exposed  to  un- 
purified  air. 

It  is  demonstrable  that  inoculation  of  the  ex- 
perimental fluid  with  a  drop  of  Hquid  known  to 
contain  living  particles  gives  rise  to  the  same 
phenomena  as  exposure  to  unpurified  air. 

And   it   is  further   certain    that    these    hvino* 

o 

particles  are  so  minute  that  the  assumption  of 
their  suspension  in  ordinary  air  presents  not  the 
slightest  difliculty.  On  the  contrary,  considering 
their  lightness  and  the  wide  diffusion  of  the 
organisms  which  produce  them,  it  is  impossible  to 


254  BIOGENESIS  AND   ABICGENESIS  viii 

conceive  that  they  should  not  be  suspended  in  the 
atmosphere  in  myriads. 

Thus  the  evidence,  direct  and  indirect,  in  favour 
of  Biogenesis  for  all  known  forms  of  life  must,  I 
think,  be  admitted  to  be  of  great  weight. 

On  the  other  side,  the  sole  assertions  worthy 
of  attention  are  that  hermetically  sealed  fluids, 
which  have  been  exposed  to  great  and  long-con- 
tinued heat,  have  sometimes  exhibited  living 
forms  of  low  organisation  when  they  have  been 
opened. 

The  first  reply  that  suggests  itself  is  the  prob- 
ability that  there  must  be  some  error  about  these 
experiments,  because  they  are  performed  on  an 
enormous  scale  every  day  with  quite  contrary 
results.  Meat,  fruits,  vegetables,  the  very  ma- 
terials of  the  most  fermentable  and  putrescible 
infusions,  are  preserved  to  the  extent,  I  suppose  I 
may  say,  of  thousands  of  tons  every  year,  by  a 
method  which  is  a  mere  application  of  Spallan- 
zani's  experiment.  The  matters  to  be  preserved 
are  well  boiled  in  a  tin  case  provided  with  a  small 
hole,  and  this  hole  is  soldered  up  when  all  the  air 
in  the  case  has  been  replaced  by  steam.  By  this 
method  they  may  be  kept  for  years  without 
putrefying,  fermenting,  or  getting  mouldy.  Now 
this  is  not  because  oxygen  is  excluded,  inasmuch 
as  it  is  now  proved  that  free  oxygen  is  not  neces- 
sary for  either  fermentation  or  putrefaction.  It 
is  not  because  the  tins  are  exhausted  of  air,  for 


VIII  BIOGENESIS   AND  ABIOGENESIS  255 

Vihriones  and  Bacteria  live,  as  Pasteur  has  shown, 
without  air  or  free  oxygen.  It  is  not  because  the 
boiled  meats  or  vegetables  are  not  putrescible  or 
fermentable,  as  those  who  have  had  the  misfortune 
to  be  in  a  ship  supplied  with  unskilfully  closed 
tins  well  know.  What  is  it,  therefore,  but  the 
exclusion  of  germs  ?  I  think  that  Abiogenists  are 
bound  to  answer  this  question  before  they  ask  us 
to  consider  new  experiments  of  precisely  the  same 
order. 

And  in  the  next  place,  if  the  results  of  the 
experiments  I  refer  to  are  really  trustworthy,  it 
by  no  means  follows  that  Abiogenesis  has  taken 
place.  The  resistance  of  living  matter  to  heat  is 
known  to  vary  within  considerable  limits,  and  to 
depend,  to  some  extent,  upon  the  chemical  and 
physical  qualities  of  the  surrounding  medium. 
But  if,  in  the  present  state  of  science,  the  alter- 
native is  offered  us, — either  germs  can  stand  a 
greater  heat  than  has  been  supposed,  or  the  mole- 
cules of  dead  matter,  for  no  valid  or  intellimble 
reason  that  is  assigned,  are  itble  to  re-arrange 
themselves  into  living  bodies,  exactly  such  as  can 
be  demonstrated  to  be  frequentl}'  produced  in 
another  way, — I  cannot  understand  how  choice 
can  be,  even  for  a  moment,  doubtful. 

But  though  I  cannot  express  this  conviction  of 
mine  too  strongly,  I  must  carefully  guard  myself 
against  the  supposition  that  I  intend  to  suggest 
that  no  such  thing  as  Abiogenesis  ever  has  taken 


256  BIOGENESIS   AND  ABIOGENESIS  vill 

place  in  the  past,  or  ever  will  take  place  in 
the  future.  With  organic  chemistry,  molecular 
physics,  and  physiology  yet  in  their  infancy,  and 
every  day  making  prodigious  strides,  I  think  it 
would  be  the  height  of  presumption  for  any  man 
to  say  that  the  conditions  under  which  matter 
assumes  the  properties  we  call  "  vital "  may  not, 
some  day,  be  artificially  brought  together.  All  I 
feel  justified  in  affirming  is,  that  I  see  no  reason 
for  believing  that  the  feat  has  been  performed 
yet. 

And  looking  back  through  the  prodigious  vista 
of  the  past,  I  find  no  record  of  the  commencement 
of  life,  and  therefore  I  am  devoid  of  any  means  of 
forming  a  definite  conclusion  as  to  the  conditions 
of  its  appearance.  Belief,  in  the  scientific  sense 
of  the  word,  is  a  serious  matter,  and  needs  strong 
foundations.  To  say,  therefore,  in  the  admitted 
absence  of  evidence,  that  I  have  any  belief  as  to 
the  mode  in  which  the  existing  forms  of  life  have 
originated,  would  be  using  words  in  a  wrong  sense. 
But  expectation  is  permissible  where  belief  is 
not ;  and  if  it  were  given  me  to  look  beyond  the 
abyss  of  geologically  recorded  time  to  the  still 
more  remote  period  when  the  earth  was  passing 
through  physical  and  chemical  conditions,  which 
it  can  no  more  see  again  than  a  man  can  recall 
his  infancy,  I  should  expect  to  be  a  witness  of  the 
evolution  of  living  protoplasm  from  not  living 
matter.     I  should  expect  to  see  it  appear  under 


V'lir  BIOGENESIS   AND   ABIOGENESIS  257 

forms  of  great  simplicity,  endowed,  like  existing 
fungi,  with  the  power  of  determining  the  formation 
of  new  protoplasm  from  such  matters  as  ammonium 
carbonates,  oxalates  and  tartrates,  alkaline  and 
earthy  phosphates,  and  water,  without  the  aid  of 
light.  That  is  the  expectation  to  which  analogi- 
cal reasoning  leads  me ;  but  I  beg  you  once  more 
to  recollect  that  I  have  no  right  to  call  my 
opinion  anything  but  an  act  of  philosophical 
faith. 

So  much  for  the  history  of  the  progress  of 
Redi's  great  doctrine  of  Biogenesis,  which  appears 
to  me,  with  the  limitations  I  have  expressed,  to 
be  victorious  along  the  whole  line  at  the  present 
day. 

As  regards  the  second  problem  offered  to  us  by 
Redi,  whether  Xenogenesis  obtains,  side  by  side 
with  Homogenesis, — whether,  that  is,  there  exist 
not  only  the  ordinary  living  things,  giving  rise  to 
offspring  which  run  through  the  same  cycle  as 
themselves,  but  also  others,  producing  offspring 
which  are  of  a  totally  different  character  from 
themselves, — the  researches  of  two  centuries  have 
led  to  a  different  result.  That  the  grubs  found 
in  galls  are  no  product  of  the  plants  on 
which  the  galls  grow,  but  are  the  result  of  the 
introduction  of  the  eggs  of  insects  into  the  sub- 
stance of  these  plants,  was  made  out  by  Vallisnieri, 
Reaumur,  and  others,  before  the  end  of  the  first 
half  of  the  eighteenth  century.     The  tapeworms, 

203 


258  BIOGENESIS   AXD   ABIOGENESIS  viii 

bladderworms,  and  flukes  continued  to  be  a 
stronghold  of  the  advocates  of  Xenogenesis  for  a 
much  longer  period.  Indeed,  it  is  only  within  the 
last  thirty  years  that  the  splendid  patience  of  Von 
Siebold,  Van  Beneden,  Leuckart,  Kuchenmeister, 
and  other  helminthologists,  has  succeeded  in 
tracing  every  such  parasite,  often  through  the 
strangest  wanderings  and  metamorphoses,  to  an 
egg  derived  from  a  parent,  actually  or  potentially 
like  itself;  and  the  tendency  of  inquiries  else- 
where has  all  been  in  the  same  direction.  A 
plant  may  throw  off  bulbs,  but  these,  sooner  or 
later,  give  rise  to  seeds  or  spores,  which  develop 
into  the  original  form.  A  poh^pe  may  give  rise 
to  Medusae,  or  a  pluteus  to  an  Echinoderm,  but 
the  Medusa  and  the  Echinoderm  give  rise  to  eggs 
which  produce  polypes  or  plutei,  and  they  are 
therefore  only  stages  in  the  cycle  of  life  of  the 
species. 

But  if  we  turn  to  pathology,  it  offers  us  some 
remarkable  approximations  to  true  Xenogenesis. 

As  I  have  already  mentioned,  it  has  been 
known  since  the  time  of  Vallisnieri  and  of 
Reaumur,  that  galls  in  plants,  and  tumours  in 
cattle,  are  caused  by  insects,  which  lay  their  eggs 
in  those  parts  of  the  animal  or  vegetable  frame  of 
which  these  morbid  structures  are  outgrowths. 
Again,  it  is  a  matter  of  familiar  experience  to 
everybody  that  mere  pressure  on  the  skin  will 
give  rise  to  a  corn.     Now  the  gall,  the  tumour. 


Viir  BIOGENESIS   AND  ABIOGENESIS  259 

and  the  corn  are  parts  of  the  living  body,  which 
have  become,  to  a  certain  degree,  independent  and 
distinct  organisms.  Under  the  influence  of  cer- 
tain external  conditions,  elements  of  the  body, 
which  should  have  developed  in  due  subordination 
to  its  general  plan,  set  up  for  themselves  and 
apply  the  nourishment  which  they  receive  to  their 
own  purposes. 

From  such  innocent  productions  as  corns  and 
warts,  there  are  all  gradations  to  the  serious 
tumours  which,  by  their  mere  size  and  the 
mechanical  obstruction  they  cause,  destroy  the 
organism  out  of  which  they  are  developed  ;  while, 
finally,  in  those  terrible  structures  known  as 
cancers,  the  abnormal  growth  has  acquired  powers 
of  reproduction  and  multiplication,  and  is  only 
morphologically  distinguishable  from  the  parasitic 
worm,  the  life  of  which  is  neither  more  nor  less 
closely  bound  up  with  that  of  the  infested 
organism. 

If  there  were  a  kind  of  diseased  structure,  the 
histological  elements  of  which  were  capable  of 
maintaining  a  separate  and  independent  existence 
out  of  the  body,  it  seems  to  me  that  the  shadowy 
boundary  between  morbid  growth  and  Xeno- 
genesis  would  be  effaced.  And  I  am  inclmed  to 
think  that  the  progress  of  discovery  has  almost 
brought  us  to  this  point  already.  I  have  been 
favoured  by  Mr.  Simon  with  an  early  copy  of  the 
last  published  of  the  valuable  "  Reports  on  the 


260  BIOGENESIS   AND   ABIOGENESIS  viii 

Public  Health,"  wliich,  in  his  capacity  of  their 
medical  officer,  he  annually  presents  to  the  Lords 
of  the  Privy  Council.  The  appendix  to  this 
report  contains  an  introductory  essay  "  On  the 
Intimate  Pathology  of  Contagion,"  by  Dr.  Burdon- 
Sanderson,  which  is  one  of  the  clearest,  most 
comprehensive,  and  well-reasoned  discussions  of  a 
great  question  which  has  come  under  my  notice 
for  a  long  time.  I  refer  you  to  it  for  details  and 
for  the  authorities  for  the  statements  I  am  about 
to  make. 

You  are  familiar  with  what  happens  in  vaccina- 
tion A  minute  cut  is  made  in  the  skin,  and  an 
infinitesimal  quantity  of  vaccine  matter  is  mserted 
into  the  wound.  Within  a  certain  time  a  vesicle 
appears  in  the  place  of  the  wound,  and  the  fluid 
which  distends  this  vesicle  is  vaccine  matter,  in 
quantity  a  hundred  or  a  thousandfold  that  which 
was  originally  inserted.  Now  what  has  taken 
place  in  the  course  of  this  operation  ?  Has  the 
vaccine  matter,  by  its  irritative  property,  produced 
a  mere  blister,  the  fluid  of  which  has  the  same 
irritative  property?  Or  does  the  vaccine  matter 
contain  living  particles,  which  have  grown  and 
multiplied  where  they  have  been  planted  ?  The 
observations  of  M.  Chauveau,  extended  and  con- 
firmed by  Dr.  Sanderson  himself,  appear  to  leave 
no  doubt  upon  this  head.  Experiments,  similar 
in  principle  to  those  of  Helmholtz  on  fermentation 
and   putrefaction,  have   proved    that   the  active 


VIII  BIOGENESIS  AND   ABIOGENESIS  261 

element  in  the  vaccine  lympli  is  non-diffusible, 
and  consists  of  minute  particles  not  exceeding 
Yoooo^^  of  an  inch  in  diameter,  which  are  made 
visible  in  the  lymj)h  by  the  microscope.  Similar 
experiments  have  proved  that  two  of  the  most 
destructive  of  epizootic  diseases,  sheep-pox  and 
glanders,  are  also  dependent  for  their  existence 
and  their  propagation  upon  extremely  small  living 
soHd  particles,  to  which  the  title  of  microzymes  is 
appHed.  An  animal  suffering  under  either  of 
these  terrible  diseases  is  a  source  of  infection  and 
contagion  to  others,  for  precisely  the  same  reason 
as  a  tub  of  fermenting  beer  is  capable  of  pro- 
pagating its  fermentation  by  "infection,"  or 
"contagion,"  to  fresh  wort.  In  both  cases  it  is 
the  solid  living  particles  which  are  efficient ;  the 
liquid  in  which  they  float,  and  at  the  expense  of 
which  they  live,  being  altogether  passive. 

Now  arises  the  question,  are  these  microzjTnes 
the  results  of  Homogenesis^  or  of  Xcnogenesis  ?  are 
they  capable,  like  the  Tm^ulce  of  yeast,  of  arising 
only  by  the  development  of  pre-existing  germs? 
or  may  they  be,  hke  the  constituents  of  a  nut-gall, 
the  results  of  a  modification  and  individuahsation 
of  the  tissues  of  the  body  in  which  they  are 
found,  resulting  from  the  operation  of  certain 
conditions  ?  Are  they  parasites  in  the  zoological 
sense,  or  are  they  merely  what  Virchow  has  called 
"  heterologous  growths  "  ?  It  is  obvious  that  this 
question    has    the     most    profound    importance. 


262  BIOGENESIS   AND  ABIOGENESIS  vin 

whether  we  look  at  it  from  a  practical  or  from  a 
theoretical  point  of  view.  A  parasite  may  be 
stamped  out  by  destroying  its  germs,  but  a  patho- 
logical product  can  only  be  annihilated  by 
removing  the  conditions  which  give  rise  to  it. 

It  appears  to  me  that  this  great  problem  will 
have  to  be  solved  for  each  z}Tnotic  disease 
separately,  for  analogy  cuts  two  ways.  I  have 
dwelt  upon  the  analogy  of  pathological  modifi- 
cation, which  is  in  favour  of  the  xenogenetic 
origin  of  microzymes;  but  I  must  now  speak 
of  the  equally  strong  analogies  in  favour  of  the 
origin  of  such  pestiferous  particles  by  the  ordinary 
process  of  the  generation  of  like  from  like. 

It  is,  at  present,  a  well-established  fact  that 
certain  diseases,  both  of  plants  and  of  animals, 
which  have  all  the  characters  of  contagious  and 
infectious  epidemics,  are  caused  by  minute  organ- 
isms. The  smut  of  wheat  is  a  weU-known  instance 
of  such  a  disease,  and  it  cannot  be  doubted  that 
the  grape-disease  and  the  potato-disease  fall 
under  the  same  category.  Among  animals, 
insects  are  wonderfully  liable  to  the  ravages  of 
contagious  and  infectious  diseases  caused  by 
microscopic  Fungi. 

In  autumn,  it  is  not  uncommon  to  see  flies 
motionless  upon  a  window-pane,  with  a  sort  of 
magic  circle,  in  white,  drawn  round  them.  On 
microscopic  examination,  the  magic  circle  is  found 
to  consist  of  innumerable  spores,  which  have  been 


Viir  BIOGENESIS   AND   ABIOGENESIS  263 

thrown  off  in  all  directions  by  a  minute  fungus 
called  Empitsa  muscce,  the  spore -forming  filaments 
of  which  stand  out  like  a  pile  of  velvet  from  the 
body  of  the  fly.  These  spore-forming  filaments 
are  connected  with  others  which  fill  the  interior 
of  the  fly's  body  like  so  much  fine  wool,  having 
eaten  away  and  destroyed  the  creature's  viscera. 
This  is  the  full-grown  condition  of  the  Unijmsa. 
If  traced  back  to  its  earliest  stages,  in  flies  which 
are  still  active,  and  to  all  appearance  healthy,  it 
is  found  to  exist  in  the  form  of  minute  corpuscles 
which  float  in  the  blood  of  the  fly.  These  multiply 
and  lengthen  into  filaments,  at  the  expense  of 
the  fly's  substance ;  and  when  they  have  at  last 
killed  the  patient,  they  grow  out  of  its  body  and 
give  off  spores.  Healthy  flies  shut  up  with 
diseased  ones  catch  this  mortal  disease,  and 
perish  like  the  others.  A  most  competent 
observer,  M.  Cohn,  who  studied  the  development 
of  the  Emimsa  very  carefully,  was  utterly  unable 
to  discover  in  what  manner  the  smallest  germs 
of  the  Emintsa  got  into  the  fly.  The  spores 
could  not  be  made  to  give  rise  to  such  germs  by 
cultivation ;  nor  were  such  germs  discoverable  in 
the  air,  or  in  the  food  of  the  fly.  It  looked 
exceedingly  like  a  case  of  Abiogenesis,  or,  at  any 
rate,  of  Xenogenesis ;  and  it  is  only  quite  recently 
that  the  real  course  of  events  has  been  made  out. 
It  has  been  ascertained,  that  when  one  of  the 
spores  falls  upon  the  body  of  a  fly,  it  begins  to 


264  BIOGENESIS   AND   ABIOGENESIS  vill 

germinate,  and  sends  out  a  process  which  bores 
its  way  through  the  fly's  skin ;  this,  having 
reached  the  interior  cavities  of  its  body,  gives 
off  the  minute  floating  corpuscles  which  are  the 
earhest  stage  of  the  EmjDUsa.  The  disease  is 
"  contagious,"  because  a  healthy  fly  coming  in 
contact  with  a  diseased  one,  from  which  the 
spore-bearing  filaments  protrude,  is  pretty  sure 
to  carry  off  a  spore  or  two.  It  is  "  infectious " 
because  the  spores  become  scattered  about  all 
sorts  of  matter  in  the  neighbourhood  of  the  slain 
flies. 

The  silkworm  has  long  been  known  to  be 
subject  to  a  very  fatal  and  infectious  disease 
called  the  Muscardine.  Audouin  transmitted  it 
by  inoculation.  This  disease  is  entirely  due  to 
the  development  of  a  fungus,  Botrytis  Bassiana, 
in  the  body  of  the  caterpillar ;  and  its  contagious- 
ness and  infectiousness  are  accounted  for  in  the 
same  way  as  those  of  the  fly-disease.  But,  of 
late  years,  a  still  more  serious  epizootic  has 
appeared  among  the  silkworms ;  and  I  may 
mention  a  few  facts  which  will  give  you  some 
conception  of  the  gravity  of  the  injury  which  it 
has  inflicted  on  France  alone. 

The  production  of  silk  has  been  for  centuries 
an  important  branch  of  industry  in  Southern 
France,  and  in  the  year  1853  it  had  attained 
such  a  magnitude  that  the  annual  produce  of  the 
French  sericulture  was  estimated  to  amount  to  a 


VIII  BIOGENESIS  AND   ABIOGENESIS  265 

tenth  of  that  of  the  whole  world,  and  represented  a 
money- value  of  117,000,000  francs,  or  nearly  five 
millions  sterling.  What  may  be  the  sum  which 
would  represent  the  money-value  of  all  the  in- 
dustries connected  with  the  working  up  of  the 
raw  silk  thus  produced,  is  more  than  I  can 
pretend  to  estimate.  Suffice  it  to  say,  that  the 
city  of  Lyons  is  built  upon  French  silk  as  much 
as  Manchester  was  upon  American  cotton  before 
the  civil  war. 

Silkworms  are  liable  to  many  diseases ;  and, 
even  before  1853,  a  peculiar  epizootic,  frequently 
accompanied  by  the  appearance  of  dark  spots 
upon  the  skin  (whence  the  name  of  "  Pebrine  " 
which  it  has  received),  had  been  noted  for  its 
mortality.  But  in  the  years  following  1853  this 
malady  broke  out  with  such  extreme  violence, 
that,  in  1858,  the  silk -crop  was  reduced  to  a  third 
of  the  amount  which  it  had  reached  in  1853 ; 
and,  up  till  within  the  last  year  or  two,  it  has 
never  attained  half  the  yield  of  1853.  This 
means  not  only  that  the  great  number  of  people 
engaged  in  silk  growing  are  some  thirty  millions 
sterling  poorer  than  they  might  have  been;  it 
means  not  only  that  high  prices  have  had  to  be 
paid  for  imported  silkworm  eggs,  and  that,  after 
investing  his  money  in  them,  in  pajdng  for  mul- 
berry-leaves and  for  attendance,  the  cultivator  has 
constantly  seen  his  silkworms  perish  and  himself 
plunged  in  ruin;  but  it  means. that  the  looms  of 


2G6  BIOGENESIS   AND  ABIOGENESIS  vrii 

Lyons  have  lacked  employment,  and  that,  for 
years,  enforced  idleness  and  misery  have  been 
the  portion  of  a  vast  population  which,  in  former 
days,  was  industrious  and  well-to-do. 

In  1858  the  gravity  of  the  situation  caused  the 
French  Academy  of  Sciences  to  appoint  Com- 
missioners, of  whom  a  distinguished  naturalist, 
M.  de  Quatrefages,  was  one,  to  inquire  into  the 
nature  of  this  disease,  and,  if  possible,  to  devise 
some  means  of  staying  the  plague.  In  reading 
the  Report  ^  made  by  M.  de  Quatrefages  in  1859, 
it  is  exceedingly  interesting  to  observe  that  his 
elaborate  study  of  the  Pebrine  forced  the  convic- 
tion upon  his  mind  that,  in  its  mode  of  occurrence 
and  propagation,  the  disease  of  the  silkworm  is,  in 
every  respect,  comparable  to  the  cholera  among 
mankind.  But  it  differs  from  the  cholera,  and  so 
far  is  a  more  formidable  malady,  in  being  here- 
ditary, and  in  being,  under  some  circumstances, 
contagious  as  well  as  infectious. 

The  Italian  naturalist,  Filippi,  discovered  in  the 
blood  of  the  silkworms  affected  by  this  strange 
disorder  a  multitude  of  cyHndrical  corpuscles,  each 
about  6  oVo^ii  of  ^^  i^^^^  long.  These  have  been 
carefully  studied  by  Lebert,  and  named  by  him 
Fanhistophyton  ;  for  the  reason  that  in  subjects  in 
which  the  disease  is  strongly  developed,  the  cor- 
puscles swarm  in  every  tissue  and  organ  of  the 
body,  and  even  pass  into  the  undeveloped  eggs  of 

1  Et'ides  sur  les  Maladiea  actuelles  des  Vers  d  Soie,  p.  53. 


Vin  BIOGENESIS  AND   ABIOGENESIS  267 

the  female  moth.  But  are  these  corpuscles 
causes,  or  mere  concomitants,  of  the  disease  ? 
Some  naturalists  took  one  view  and  some  another ; 
and  it  was  not  until  the  French  Government, 
alarmed  by  the  continued  ravages  of  the  malady, 
and  the  inefficiency  of  the  remedies  which  had 
been  suggested,  despatched  M.  Pasteur  to  study  it, 
that  the  question  received  its  final  settlement ;  at 
a  great  sacrifice,  not  only  of  the  time  and  peace  of 
mind  of  that  eminent  philosopher,  but,  I  regret  to 
have  to  add,  of  his  health. 

But  the  sacrifice  has  not  been  in  vain.  It  is 
now  certain  that  this  devastating,  cholera-like, 
Pebrine,  is  the  effect  of  the  growth  and  multiplica- 
tion of  the  Fanhisto'phyton  in  the  silkworm.  It  is 
contagious  and  infectious,  because  the  corpuscles 
of  the  Parihisto'phyton  pass  away  from  the  bodies 
of  the  diseased  caterpillars,  directly  or  indirectly, 
to  the  alimentary  canal  of  healthy  silkworms  in 
their  neighbourhood ;  it  is  hereditary  because  the 
corpuscles  enter  into  the  eggs  while  they  are  being 
formed,  and  consequently  are  carried  within  them 
when  they  are  laid  ;  and  for  this  reason,  also,  it 
presents  the  very  singular  peculiarity  of  being 
inherited  only  on  the  mother's  side.  There  is 
not  a  single  one  of  all  the  apparently  capricious 
and  unaccountable  phenomena  presented  by  the 
Pebrine,  but  has  received  its  explanation  from  the 
fact  that  the  disease  is  the  result  of  the  presence 
of  the  microscopic  organism  Panhistojphyton. 


268  BIOGENESIS   AND   ABIOGENESIS  viii 

Such  being  the  facts  with  respect  to  the  Pebrine, 
v/hat  are  the  indications  as  to  the  method  of  pre- 
venting it  ?  It  is  obvious  that  this  depends  upon 
the  way  in  which  the  Panhistcphyton  is  generated. 
If  it  may  be  generated  by  Abiogenesis,  or  by 
Xenogenesis,  within  the  silkworm  or  its  moth,  the 
extirpation  of  the  disease  must  depend  upon  the 
prevention  of  the  occurrence  of  the  conditions 
under  which  this  generation  takes  place.  But  if, 
on  the  other  hand,  the  Paiihistophytcn  is  an  inde- 
pendent organism,  which  is  no  more  generated  by 
the  silkworm  than  the  mistletoe  is  generated  by 
the  apple-tree  or  the  oak  on  which  it  grows, 
though  it  may  need  the  silkworm  for  its  develop- 
ment in  the  same  way  as  the  mistletoe  needs  the 
tree,  then  the  indications  are  totally  different. 
The  sole  thing  to  be  done  is  to  get  rid  of  and  keep 
away  the  germs  of  the  Fanhistophyton.  As  might 
be  imagined,  from  the  course  of  his  previous  inves- 
tigations, M.  Pasteur  was  led  to  believe  that  the 
latter  was  the  right  theory ;  and,  guided  by  that 
theory,  he  has  devised  a  method  of  extirpating  the 
disease,  which  has  proved  to  be  completely  success- 
ful wherever  it  has  been  properly  carried  out. 

There  can  be  no  reason,  then,  for  doubting  that, 
among  insects,  contagious  and  infectious  diseases, 
of  great  malignity,  are  caused  by  minute  organisms 
which  are  produced  from  pre-existing  germs,  or  by 
homogenesis ;  and  there  is  no  reason,  that  I  know 
of,  for  believing  that  what  happens  in  insects  may 


VIII  BIOGENESIS  AND   ABIOGENESIS  269 

not  take  place  in  the  highest  animals.  Indeed, 
there  is  already  strong  evidence  that  some  diseases 
of  an  extremely  malignant  and  fatal  character  to 
which  man  is  subject,  are  as  much  the  work  of 
minute  organisms  as  is  the  Pebrine.  I  refer  for 
this  evidence  to  the  very  striking  facts  adduced 
by  Professor  Lister  in  his  various  well-known 
pubHcations  on  the  antiseptic  method  of  treat- 
ment. It  appears  to  me  impossible  to  rise  from 
the  perusal  of  those  publications  without  a  strong 
conviction  that  the  lamentable  mortality  which  so 
frequently  dogs  the  footsteps  of  the  most  skilful 
operator,  and  those  deadly  consequences  of  wounds 
and  injuries  which  seem  to  haunt  the  very  walls 
of  great  hospitals,  and  are,  even  now,  destroying 
more  men  than  die  of  bullet  or  bayonet,  are  due 
to  the  importation  of  minute  organisms  into 
wounds,  and  their  increase  and  multiplication ;  and 
that  the  surgeon  who  saves  most  lives  will  be  he 
who  best  works  out  the  practical  consequences  of 
the  hypothesis  of  Redi. 

■  I  commenced  this  Address  by  asking  you  to 
follow  me  in  an  attempt  to  trace  the  path  which 
has  been  followed  by  a  scientific  idea,  in  its  long 
and  slow  progress  from  the  position  of  a  probable 
hypothesis  to  that  of  an  established  law  of  nature. 
Our  survey  has  not  taken  us  into  very  attractive 
regions  ;  it  has  lain,  chiefly,  in  a  land  flowing  with 
the  abominable,  and  peopled  with  mere  grubs  and 
mouldiness.     And  it  may  be  imagined  with  what 


270  BIOGENESIS  AND   ABIOGENESIS  vill 

smiles  and  shrugs,  practical  and  serious  contempo- 
raries of  Redi  and  of  Spallanzani  may  have  com- 
mented on  the  waste  of  their  high  abilities  in 
toiling  at  the  solution  of  problems  which,  though 
curious  enough  in  themselves,  could  be  of  no  con- 
ceivable utility  to  mankind. 

Nevertheless,  you  will  have  observed  that  before 
we  had  travelled  very  far  upon  our  road,  there 
appeared,  on  the  right  hand  and  on  the  left, 
fields  laden  with  a  harvest  of  golden  grain, 
immediately  convertible  into  those  things  which 
the  most  solidly  practical  men  will  admit  to  have 
value — viz.,  money  and  life. 

The  direct  loss  to  France  caused  by  the  Pebrine 
in  seventeen  years  cannot  be  estimated  at  less 
than  fifty  milHons  sterling;  and  if  we  add  to 
this  what  Redi's  idea,  in  Pasteur's  hands,  has 
done  for  the  wine-grower  and  for  the  vinegar- 
maker,  and  try  to  capitalise  its  value,  we  shall 
find  that  it  will  go  a  long  way  towards  repairing 
the  money  losses  caused  by  the  frightful  and 
calamitous  war  of  this  autumn.  And  as  to  the 
equivalent  of  Redi's  thought  in  Hfe,  how  can  we 
over-estimate  the  value  of  that  knowledge  of  the 
nature  of  epidemic  and  epizootic  diseases,  and 
consequently  of  the  means  of  checking,  or  eradi- 
cating them,  the  da^vn  of  which  has  assuredly 
commenced  ? 

Looking  back  no  further  than  ten  years,  it  is 
possible  to  select  three  (1863,  1864,  and  1869)  in 


VIII  BIOGENESIS  AND   ABIOGENESIS  271 

which  the  total  number  of  deaths  from  scarlet- 
fever  alone  amounted  to  ninety  thousand.  That 
is  the  return  of  killed,  the  maimed  and  disabled 
being  left  out  of  sight.  Why,  it  is  to  be  hoped 
that  the  list  of  killed  in  the  present  bloodiest 
of  all  wars  will  not  amount  to  more  than  this  1 
But  the  facts  which  I  have  placed  before  you 
must  leave  the  least  sanguine  without  a  doubt 
that  the  nature  and  the  causes  of  this  scourge 
will,  one  day,  be  as  well  understood  as  those 
of  the  Pebrine  are  now;  and  that  the  long- 
suffered  massacre  of  our  innocents  will  come  to 
an  end. 

And  thus  mankind  will  have  one  more  admoni- 
tion that  "  the  people  perish  for  lack  of  know- 
ledge " ;  and  that  the  alleviation  of  the  miseries, 
and  the  promotion  of  the  welfare,  of  men  must 
be  sought,  by  those  who  will  not  lose  their  pains, 
in  that  diligent,  patient,  loving  study  of  all  the 
multitudinous  aspects  of  Nature,  the  results  of 
which  constitute  exact  knowledge,  or  Science. 
It  is  the  justification  and  the  glory  of  this  great 
meeting  that  it  is  gathered  together  for  no  other 
object  than  the  advancement  of  the  moiety  of 
science  which  deals  with  those  phenomena  of 
nature  which  we  call  physical.  May  its  en- 
deavours be  crowned  with  a  full  measure  of 
success  I 


IX 


GEOLOGICAL   CONTEMPORANEITY  AND 
PERSISTENT  TYPES  OF  LIFE 

[1862] 

Merchants  occasionally  go  through  a  wholesome, 
though  troublesome  and  not  always  satisfactory, 
process  which  they  term  "  taking  stock."  After 
aU  the  excitement  of  speculation,  the  pleasure  of 
gain,  and  the  pain  of  loss,  the  trader  makes  up  his 
mind  to  face  facts  and  to  learn  the  exact  quantity 
and  quality  of  his  solid  and  reliable  possessions. 

The  man  of  science  does  well  sometimes  to 
imitate  this  procedure ;  and,  forgetting  for  the 
time  the  importance  of  his  own  small  winnings, 
to  re-examine  the  common  stock  in  trade,  so  that 
he  may  make  sure  how  far  the  .stock  of  bullion  in 
the  cellar — on  the  faith  of  whose  existence  so 
much  paper  has  been  circulating — is  really  the 
solid  gold  of  truth. 

The   Anniversary  Meeting   of    the    Geological 


IX 


GEOLOGICAL   CONTEMPORANEITY  273 


Society  seems  to  be  an  occasion  well  suited  for  an 
undertaking  of  this  kind — for  an  inquiry,  in  fact, 
into  the  nature  and  value  of  the  present  results 
of  palaeontological  investigation ;  and  the  more 
so,  as  all  those  who  have  paid  close  attention  to 
the  late  multitudinous  discussions  in  which 
palaeontology  is  implicated,  must  have  felt  the 
urgent  necessity  of  some  such  scrutiny. 

First  in  order,  as  the  most  definite  and  unques- 
tionable of  all  the  results  of  palaeontology,  must 
be  mentioned  the  immense  extension  and  impulse 
given  to  botany,  zoology,  and  comparative  an- 
atomy, by  the  investigation  of  fossil  remains. 
Indeed,  the  mass  of  biological  facts  has  been  so 
greatly  increased,  and  the  range  of  biological 
speculation  has  been  so  vastly  widened,  by  the 
researches  of  the  geologist  and  palaeontologist, 
that  it  is  to  be  feared  there  are  naturalists  in 
existence  who  look  upon  geology  as  Brindley 
regarded  rivers.  "  Rivers,"  said  the  great  engineer, 
"  were  made  to  feed  canals  ; "  and  geology,  some 
seem  to  think,  was  solely  created  to  advance  com- 
parative anatomy. 

Were  such  a  thought  justifiable,  it  could 
hardly  expect  to  be  received  with  favour  by  this 
assembly.  But  it  is  not  justifiable.  Your  favourite 
science  has  her  own  great  aims  independent  of  all 
others ;  and  if,  notwithstanding  her  steady  devotion 
to  her  own  progress,  she  can  scatter  such  rich 
alms  among  her  sisters,  it  should  be  remembered 

204 


274  GEOLOGICAL  CONTEMPORANEITY  is 

that  her  charity  is  of  the  sort  that  does  not 
impoverish,  but  "blesseth  him  that  gives  and  him 
that  takes." 

Regard  the  matter  as  we  will,  however,  the 
facts  remain.  Nearly  40,000  species  of  animals 
and  plants  have  been  added  to  the  S3^stema 
Naturae  by  palseontological  research.  This  is  a 
living  population  equivalent  to  that  of  a  new 
continent  in  mere  number ;  equivalent  to  that  of 
a  new  hemisphere,  if  we  take  into  account  the 
small  population  of  insects  as  yet  found  fossil,  and 
the  large  proportion  and  peculiar  organisation  of 
many  of  the  Yertebrata. 

But,  beyond  this,  it  is  perhaps  not  too  much 
to  say  that,  except  for  the  necessity  of  interpreting 
palaeontological  facts,  the  laws  of  distribution 
would  have  received  less  careful  study;  while 
few  comparative  anatomists  (and  those  not  of  the 
first  order)  would  have  been  induced  by  mere 
love  of  detail,  as  such,  to  study  the  minutiae  of 
osteology,  were  it  not  that  in  such  minutiae  lie  the 
only  keys  to  the  most  interesting  riddles  offered 
by  the  extinct  animal  world. 

These  assuredly  are  great  and  solid  gains.  Surely 
it  is  matter  for  no  small  congratulation  that  in 
half  a  century  (for  palaeontology,  though  it  dawned 
earlier,  came  into  full  day  only  with  Cuvier)  a 
subordinate  branch  of  biology  should  have  doubled 
the  value  and  the  interest  of  the  whole  group 
of  sciences  to  which  it  belongs. 


IX 


GEOLOGICAL   CONTEMPORANEITY  275 


But  this  is  not  all.  Allied  with  geology, 
palaeontology  has  established  two  laws  of  inestim- 
able importance :  the  first,  that  one  and  the  same 
area  of  the  earth's  surface  has  been  successively 
occupied  by  very  different  kinds  of  Hving  beings  ; 
the  second,  that  the  order  of  succession  established 
in  one  locality  holds  good,  approximately,  in  all. 

The  first  of  these  laws  is  universal  and  iiTe- 
versible ;  the  second  is  an  induction  from  a  vast 
number  of  observations,  though  it  may  possibly, 
and  even  probably,  have  to  admit  of  exceptions. 
As  a  consequence  of  the  second  law,  it  follows 
that  a  peculiar  relation  frequently  subsists  between 
series  of  strata  containing  organic  remains,  in  dif- 
ferent localities.  The  series  resemble  one  another 
not  only  in  virtue  of  a  general  resemblance  of  the 
orsfanic  remains  in  the  two,  but  also  in  virtue  of  a 
resemblance  in  the  order  and  character  of  the 
serial  succession  in  each.  There  is  a  resemblance 
of  arrangement ;  so  that  the  separate  terms  of 
each  series,  as  well  as  the  whole  series,  exhibit  a 
correspondence. 

Succession  implies  time  ;  the  lower  members 
of  an  undisturbed  series  of  sedimentary  rocks  are 
certainly  older  than  the  upper;  and  when  the 
notion  of  age  was  once  introduced  as  the  equiva- 
lent of  succession,  it  was  no  wonder  that  corres- 
pondence in  succession  came  to  be  looked  upon  as 
a  correspondence  in  age,  or  "contemporaneity." 
And,  indeed,  so  long  as  relative  age  only  is  spoken 


276  GEOLOGICAL   CONTEMPORANEITY  ix 

of,  correspondence  in  succession  is  correspondence 
in  age ;    it  is  relative  contemporaneity. 

But  it  would  have  been  very  mucti  better  for 
geology  if  so  loose  and  ambiguous  a  word  as 
"contemporaneous"  had  been  excluded  from  her 
terminology,  and  if,  in  its  stead,  some  term 
expressing  similarity  of  serial  relation,  and  ex- 
cluding the  notion  of  time  altogether,  had  been 
employed  to  denote  correspondence  in  position 
in  two  or  more  series  of  strata. 

In  anatomy,  Avhere  such  correspondence  of  posi- 
tion has  constantly  to  be  spoken  of,  it  is  denoted 
by  the  word  "  homology  "  and  its  derivatives ;  and 
for  Geology  (which  after  all  is  only  the  anatomy 
and  physiology  of  the  earth)  it  might  be  well  to 
invent  some  single  word,  such  as  "homotaxis" 
(similarity  of  order),  in  order  to  express  an  essen- 
tially similar  idea.  This,  however,  has  not  been 
done,  and  most  probably  the  inquiry  will  at  once 
be  made — To  what  end  burden  science  with  a  new 
and  strange  term  in  place  of  one  old,  familiar,  and 
part  of  our  common  language  ? 

The  reply  to  this  question  will  become  obvious 
as  the  inquiry  into  the  results  of  palaBontology  is 
pushed  further. 

Those  whose  business  it  is  to  acquaint  themselves 
specially  with  the  works  of  palaeontologists,  in  fact, 
will  be  fully  aware  that  very  few,  if  any,  would  rest 
satisfied  with  such  a  statement  of  the  conclusions 


IX  GEOLOGICAL  CONTEMPORANEITY  277 

of  their  branch  of  biology  as  that  which  has  just 
been  given. 

Our  standard  repertories  of  palaeontology  profess 
to  teach  us  far  higher  things — to  disclose  the 
entire  succession  of  living  forms  upon  the  surface 
of  the  globe ;  to  tell  us  of  a  wholly  different  dis- 
tribution of  climatic  conditions  in  ancient  times  ; 
to  reveal  the  character  of  the  first  of  all  hving 
existences ;  and  to  trace  out  the  law  of  progi'ess 
from  them  to  us. 

It  may  not  be  unprofitable  to  bestow  on  these 
professions  a  somewhat  more  critical  examination 
than  they  have  hitherto  received,  in  order  to 
ascertain  how  far  they  rest  on  an  irrefragable 
basis ;  or  whether,  after  all,  it  might  not  be  well 
for  palaeontologists  to  learn  a  little  more  carefully 
that  scientific  "  ars  artium,"  the  art  of  saying  '•'  I 
don't  know."  And  to  this  end  let  us  define  some- 
what more  exactly  the  extent  of  these  pretensions 
of  palaeontology. 

Every  one  is  aware  that  Professor  Bronn's  "  Un- 
tersuchungen  "  and  Professor  Pictet's  "  Traite  de 
Paleontologie "  are  works  of  standard  authority, 
familiarly  consulted  by  every  working  palaeontolo- 
gist. It  is  desirable  to  speak  of  these  excellent 
books,  and  of  their  distinguished  authors,  with  the 
utmost  respect,  and  in  a  tone  as  far  as  possible  re- 
moved from  carping  criticism ;  indeed,  if  they  are 
specially  cited  in  this  place,  it  is  merely  in  justifi- 
cation of  the  assertion  that  the  following  proposi- 


278  GEOLOGICAL   CONTEMPORANEITY  ix 

tions,  which  may  be  found  implicitly,  or  explicitly, 
in  the  works  in  question,  are  regarded  by  the  mass 
of  palieontologists  and  geologists,  not  only  on  the 
Continent  but  in  this  country,  as  expressing  some 
of  the  best-established  results  of  palseontology. 
Thus  :— 

Animals  and  plants  began  their  existence  to- 
gether, not  long  after  the  commencement  of  the 
deposition  of  the  sedimentary  rocks ;  and  then 
succeeded  one  another,  in  such  a  manner,  that 
totally  distinct  faunae  and  florae  occupied  the  whole 
surface  of  the  earth,  one  after  the  other,  and  dur- 
ing distinct  epochs  of  time. 

A  geological  formation  is  the  sum  of  all  the 
strata  deposited  over  the  whole  surface  of  the 
earth  during  one  of  these  epochs :  a  geolo- 
gical fauna  or  flora  is  the  sum  of  all  the 
species  of  animals  or  plants  which  occupied  the 
whole  surface  of  the  globe,  during  one  of  these 
epochs. 

The  population  of  the  earth's  surface  was  at  first 
very  similar  in  all  parts,  and  only  from  the  middle 
of  the  Tertiary  epoch  onwards,  began  to  show  a 
distinct  distribution  in  zones. 

The  constitution  of  the  original  population,  as 
well  as  the  numerical  proportions  of  its  members, 
indicates  a  warmer  and,  on  the  whole,  somewhat 
tropical  climate,  which  remained  tolerably  equable 
throughout  the  year.  The  subsequent  distribution 
of  living  beings  in  zones  is  the  result  of  a  gradual 


IX  GEOLOGICAL  CONTEMPORANEITY  279 

lo\srering  of  the  general  temperature,  which  first 
began  to  be  felt  at  the  poles. 

It  is  not  now  proposed  to  inquire  whether  these 
doctrines  are  true  or  false ;  but  to  direct  your 
attention  to  a  much  simpler  though  very  essential 
preliminary  question — What  is  their  logical  basis  ? 
what  are  the  fundamental  assumptions  upon  which 
they  all  logically  depend  ?  and  what  is  the  evidence 
on  which  those  fundamental  propositions  demand 
our  assent  ? 

These  assumptions  are  two  :  the  first,  that  the 
commencement  of  the  geological  record  is  coeval 
with  the  commencement  of  life  on  the  globe ;  the 
second,  that  geological  contemporaneity  is  the 
same  thing  as  chronological  s}Tichrony.  Without 
the  first  of  these  assumptions  there  would  of 
course  be  no  ground  for  any  statement  respecting 
the  commencement  of  life ;  without  the  second,  all 
the  other  statements  cited,  every  one  of  which 
implies  a  knowledge  of  the  state  of  different  parts 
of  the  earth  at  one  and  the  same  time,  will  be  no 
less  devoid  of  demonstration. 

The  first  assumption  obviously  rests  entirely  on 
negative  evidence.  This  is,  of  course,  the  only 
evidence  that  ever  can  be  available  to  prove  the 
commencement  of  any  series  of  phenomena ;  but, 
at  the  same  time,  it  must  be  recollected  that  the 
value  of  negative  evidence  depends  entirely  on  the 
amount  of  positive  corroboration  it  receives.  If  A.K 


280  GEOLOGICAL   CONTEMPORANEITY  ix 

wishes  to  prove  an  alibi,  it  is  of  no  use  for  him  to 
get  a  thousand  witnesses  simply  to  swear  that 
they  did  not  see  him  in  such  and  such  a  place, 
unless  the  witnesses  are  prepared  to  prove  that 
they  must  have  seen  him  had  he  been  there.  But 
the  evidence  that  animal  life  commenced  with  the 
Lingula-flags,  e.g.,  would  seem  to  be  exactly  of  this 
unsatisfactory  uncorroborated  sort.  The  Cambrian 
witnesses  simply  swear  they  "  haven't  seen  any- 
body their  way  " ;  upon  which  the  counsel  for  the 
other  side  immediately  puts  in  ten  or  twelve 
thousand  feet  of  Devonian  sandstones  to  make 
oath  they  never  saw  a  fish  or  a  mollusk,  though 
all  the  world  knows  there  were  plenty  in  their 
time. 

But  then  it  is  urged  that,  though  the  Devonian 
rocks  in  one  part  of  the  world  exhibit  no  fossils, 
in  another  they  do,  while  the  lower  Cambrian 
rocks  nowhere  exhibit  fossils,  and  hence  no  living 
being  could  have  existed  in  their  epoch. 

To  this  there  are  two  replies :  the  first  that  the 
observational  basis  of  the  assertion  that  the  lowest 
rocks  are  nowhere  fossiliferous  is  an  amazingly 
small  one,  seeing  how  very  small  an  area,  in  com- 
parison to  that  of  the  whole  world,  has  yet  been 
fully  searched ;  the  second,  that  the  argument  is 
good  for  nothing  unless  the  unfossiliferous  rocks 
in  question  were  not  only  contemporaneous  in  the 
geological  sense,  but  synchronous  in  the  chronolo- 
gical sense.     To  use  the  alibi  illustration  again. 


rx  GEOLOGICAL  CONTEMPORANEITY  281 

If  a  man  wislies  to  prove  he  was  in  neither  of 
two  places,  A  and  B,  on  a  given  day,  his  witnesses 
for  each  place  must  be  prepared  to  answer  for  the 
whole  day.  If  they  can  only  prove  that  he  was 
not  at  A  in  the  morning,  and  not  at  B  in  the 
afternoon,  the  evidence  of  his  absence  from  both 
is  nil,  because  he  might  have  been  at  B  in  the 
morning  and  at  A  in  the  afternoon. 

Thus  everything  depends  upon  the  validity  of 
the  second  assumption.  And  we  must  proceed  to 
inquire  what  is  the  real  meaning  of  the  word 
"  contemj)oraneous  "  as  employed  by  geologists. 
To  this  end  a  concrete  example  may  be  taken. 

The  Lias  of  England  and  the  Lias  of  Germany, 
the  Cretaceous  rocks  of  Britain  and  the  Cretaceous 
rocks  of  Southern  India,  are  termed  by  geologists 
"  contemporaneous "  formations  ;  but  whenever 
any  thoughtful  geologist  is  asked  whether  he 
means  to  say  that  they  were  deposited  synchron- 
ously, he  says,  "  No, — only  within  the  same  great 
epoch."  And  if,  in  pursuing  the  inquiry,  he  is 
asked  what  may  be  the  approximate  value  in  time 
of  a  "  great  epoch  " — whether  it  means  a  hundred 
years,  or  a  thousand,  or  a  million,  or  ten  million 
years — his  reply  is,  "  I  cannot  tell." 

If  the  further  question  be  put,  whether  physical 
geology  is  in  possession  of  any  method  by  which 
the  actual  synchrony  (or  the  reverse)  of  any  two 
distant  deposits  can  be  ascertained,  no  such 
method  can  be  heard  of;  it  being  admitted  by  all 


282  GEOLOGICAL   CON  rEMPORANEITY  ix 

the  best  authorities  that  neither  similarity  of 
mineral  composition,  nor  of  physical  character, 
nor  even  direct  continuity  of  stratum,  are  absolute 
proofs  of  the  synchronism  of  even  approximated 
sedimentary  strata :  while,  for  distant  deposits, 
there  seems  to  be  no  kind  of  physical  evidence 
attainable  of  a  nature  competent  to  decide 
whether  such  deposits  were  formed  simultan- 
eously, or  whether  they  possess  any  given  differ- 
ence of  antiquity.  To  return  to  an  example 
already  given :  All  competent  authorities  will 
probably  assent  to  the  proposition  that  physical 
geology  does  not  enable  us  in  any  way  to  rejDly  to 
this  question — Were  the  British  Cretaceous  rocks 
deposited  at  the  same  time  as  those  of  India,  or 
are  they  a  million  of  years  younger  or  a  million  of 
3^ears  older  ? 

Is  palaeontology  able  to  succeed  where  physical 
geology  fails  ?  Standard  writers  on  palaeontology, 
as  has  been  seen,  assume  that  she  can.  They 
take  it  for  granted,  that  deposits  containing 
similar  organic  remains  are  synchronous — at  any 
rate  in  a  broad  sense ;  and  yet,  those  who  will 
study  the  eleventh  and  twelfth  chapters  of  Sir 
Henry  De  La  Beche's  remarkable  "  Researches 
in  Theoretical  Geology,"  published  now  nearly 
thirty  j^ears  ago,  and  will  carry  out  the  arguments 
there  most  luminously  stated,  to  their  logical 
consequences,  may  very  easily  convince  them- 
selves  that   even    absolute    identity  of    organic 


IX 


GEOLOGICAL   CONTEMPORANEITY  283 


contents  is  no  proof  of  the  s}Tichrony  of  deposits, 
while  absolute  diversity  is  no  proof  of  difference 
of  date.  Sir  Henry  De  La  Beche  goes  even 
further,  and  adduces  conclusive  evidence  to  show 
that  the  different  parts  of  one  and  the  same 
stratum,  having  a  similar  composition  throughout, 
containing  the  same  organic  remains,  and  having 
similar  beds  above  and  below  it,  may  yet  differ 
to  any  conceivable  extent  in  age. 

Edward  Forbes  was  in  the  habit  of  asserting 
that  the  similarity  of  the  organic  contents  of 
distant  formations  was  primd  facie  evidence,  not 
of  their  similarity,  but  of  their  difference  of  age ; 
and  holding  as  he  did  the  doctrine  of  single 
specific  centres,  the  conclusion  was  as  legitimate 
as  any  other ;  for  the  two  districts  must 
have  been  occuj^ied  by  migration  from  one  of 
the  two,  or  from  an  intermediate  spot,  and  the 
chances  against  exact  coincidence  of  migration 
and  of  imbedding  are  infinite. 

In  point  of  fact,  however,  whether  the  hypo- 
thesis of  single  or  of  multiple  specific  centres 
be  adopted,  similarity  of  organic  contents  cannot 
possibly  afford  any  proof  of  the  synchrony  of 
the  deposits  which  contain  them ;  on  the  con- 
trary, it  is  demonstrably  compatible  with  the 
lapse  of  the  most  prodigious  intervals  of  time, 
and.  with  the  interposition  of  vast  changes  in  the 
organic  and  inorganic  worlds,  between  the  epochs 
in  which  such  deposits  were  formed. 


284  GEOLOGICAL   CONTEMPORANEITY  ix 

On  what  amount  of  similarity  of  their  faunae 
is  the  doctrine  of  the  contemporaneity  of  the 
European  and  of  the  North  American  Silurians 
based  ?  In  the  last  edition  of  Sir  Charles  Lyell's 
"Elementary  Geology"  it  is  stated,  on  the 
authority  of  a  former  President  of  this 
Society,  the  late  Daniel  Sharpe,  that  between 
30  and  40  per  cent,  of  the  species  of  Silurian 
Mollusca  are  common  to  both  sides  of  the 
Atlantic.  By  way  of  due  allowance  for  further 
discovery,  let  us  double  the  lesser  number  and 
suj)pose  that  60  per  cent,  of  the  species  are 
common  to  the  North  American  and  the  British 
Silurians.  Sixty  per  cent,  of  species  in  common 
is,  then,  proof  of  contemporaneity. 

Now  sujDpose  that,  a  million  or  two  of  years 
hence,  when  Britain  has  made  another  dip 
beneath  the  sea  and  has  come  up  again,  some 
geologist  appHes  this  doctrine,  in  comparing  the 
strata  laid  bare  by  the  upheaval  of  the  bottom, 
say,  of  St.  George's  Channel  with  what  may  then 
remain  of  the  Suffolk  Crag.  Reasoning  in  the 
same  way,  he  will  at  once  decide  the  Suffolk 
Crag  and  the  St.  George's  Channel  beds  to  be 
contemporaneous ;  although  we  happen  to  know 
that  a  vast  period  (even  in  the  geological  sense) 
of  time,  and  physical  changes  of  almost  unpre- 
cedented extent,  separate  the  two. 

But  if  it  be  a  demonstrable  fact  that  strata 
containing  more  than  60  or  70  per  cent,  of  species 


IX  GEOLOGICAL   CONTEMPOEANEITY  285 

of  MoUusca  in  common,  and  comparatively  close 
together,  may  yet  be  separated  by  an  amount 
of  geological  time  sufficient  to  allow  of  some 
of  the  greatest  physical  changes  the  world  has 
seen,  what  becomes  of  that  sort  of  contem- 
poraneity the  sole  evidence  of  which  is  a  simi- 
larity of  facies,  or  the  identity  of  half  a  dozen 
species,  or  of  a  good  many  genera  ? 

And  yet  there  is  no  better  evidence  for  the 
contemporaneity  assumed  by  all  who  adopt  the 
hypothesis  of  universal  faunae  and  florse,  of  a 
universally  uniform  climate,  and  of  a  sensible 
cooling  of  the  globe  during  geological  time. 

There  seems,  then,  no  escape  from  the  admis- 
sion that  neither  physical  geology,  nor  palaeonto- 
logy, possesses  any  method  by  which  the  absolute 
synchronism  of  two  strata  can  be  demonstrated. 
All  that  geology  can  prove  is  local  order  of  succes- 
sion. It  is  mathematically  certain  that,  in  any 
given  vertical  linear  section  of  an  undisturbed 
series  of  sedimentary  deposits,  the  bed  which  lies 
lowest  is  the  oldest.  In  many  other  vertical 
Hnear  sections  of  the  same  series,  of  course,  cor- 
responding beds  will  occur  in  a  similar  order; 
but,  however  great  may  be  the  probability,  no 
man  can  say  with  absolute  certainty  that  the 
beds  in  the  two  sections  were  synchronously 
deposited.  For  areas  of  moderate  extent,  it  is 
doubtless  true  that  no  practical  evil  is  likely  to 
result  from  assuming  the  corresponding  beds  to 


286  GEOLOGICAL   CONTEMPORANEITY  ix 

be  synchronous  oi  strictly  contemporaneous ;  and 
there  are  multitudes  of  accessory  circumstances 
which  may  fully  justify  the  assumption  of  such 
synchrony.  But  the  moment  the  geologist  has 
to  deal  with  large  areas,  or  with  completely 
separated  deposits,  the  mischief  of  confounding 
that  "  homotaxis  "  or  "  similarity  of  arrangement," 
which  can  be  demonstrated,  with  "  synchron}^ "  or 
"identity  of  date,"  for  which  there  is  not  a 
shadow  of  proof,  under  the  one  common  term 
of  "  contemporaneity  "  becomes  incalculable,  and 
proves  the  constant  source  of  gratuitous  specu- 
lations. 

For  anything  that  geology  or  pala3ontology  are 
able  to  show  to  the  contrary,  a  Devonian  fauna 
and  flora  in  the  British  Islands  may  have  been 
contemporaneous  with  Silurian  life  in  North 
America,  and  with  a  Carboniferous  fauna  and  flora 
in  Africa.  Geographical  provinces  and  zones  may 
have  been  as  distinctly  marked  in  the  Palaeozoic 
epoch  as  at  present,  and  those  seemingly  sudden 
appearances  of  new  genera  and  species,  which  we 
ascribe  to  new  creation,  may  be  simple  results  of 
migration. 

It  may  be  so;  it  may  be  otherwise.  In  the 
present  condition  of  our  knowledge  and  of  our 
methods,  one  verdict — "not  proven,  and  not 
provable" — must  be  recorded  against  all  the 
grand  hypotheses  of  the  palaeontologist  respecting 
the  general  succession  of  Hfe  on  the  globa     The 


IX  GEOLOGICAL   COXTEMPORANEITY  287 

order  and  nature  of  terrestrial  life,  as  a  whole, 
are  open  questions.  Geology  at  present  provides 
us  with  most  valuable  topographical  records,  but 
she  has  not  the  means  of  working  them  into  a 
universal  history.  Is  such  a  universal  history, 
then,  to  be  regarded  as  unattainable  ?  Are  all 
the  grandest  and  most  interesting  problems  which 
offer  themselves  to  the  geological  student,  essenti- 
ally insoluble  ?  Is  he  in  the  position  of  a  scientific 
Tantalus — doomed  always  to  thirst  for  a  knowledge 
which  he  cannot  obtain  ?  The  reverse  is  to  be 
hoped ;  nay,  it  may  not  be  impossible  to  indicate 
the  source  whence  help  Avill  come. 

In  commencing  these  remarks,  mention  wa8 
made  of  the  great  obligations  under  which  the 
naturalist  lies  to  the  geologist  and  palaeontologist. 
Assuredly  the  time  will  come  when  these  obliga- 
tions will  be  repaid  tenfold,  and  when  the  maze  of 
the  world's  past  history,  through  which  the  pure 
geologist  and  the  pure  palaeontologist  find  no 
guidance,  will  be  securely  threaded  by  the  clue 
furnished  by  the  naturalist. 

All  who  are  competent  to  express  an  opinion  on 
the  subject  are,  at  present,  agreed  that  the  mani- 
fold varieties  of  animal  and  vegetable  form  have 
not  either  come  into  existence  by  chance,  nor 
result  from  capricious  exertions  of  creative  power ; 
but  that  they  have  taken  place  in  a  definite  order, 
the  statement  of  which  order  is  what  men  of 
science  term  a  natural  law.     Whether  such  a  law 


288  GEOLOGICAL  CONTEMPORANEITY  ix 

is  to  be  regarded  as  an  expression  of  the  mode  of 
operation  of  natural  forces,  or  whether  it  is  simply 
a  statement  of  the  manner  in  which  a  super- 
natural power  has  thought  fit  to  act,  is  a  secondary 
question,  so  long  as  the  existence  of  the  law  and 
the  possibility  of  its  discovery  by  the  human 
intellect  are  granted.  But  he  must  be  a  half- 
hearted philosopher  who,  believing  in  that  possi- 
bility, and  having  watched  the  gigantic  strides 
of  the  biological  sciences  during  the  last  twenty 
years,  doubts  that  science  will  sooner  or  later 
make  this  further  step,  so  as  to  become  possessed 
of  the  law  of  evolution  of  organic  forms — of  the 
unvarying  order  of  that  great  chain  of  causes  and 
effects  of  which  all  organic  forms,  ancient  and 
modern,  are  the  links.  And  then,  if  ever,  we 
shall  be  able  to  begin  to  discuss,  with  profit,  the 
questions  respecting  the  commencement  of  life, 
and  the  nature  of  the  successive  populations  of 
the  globe,  which  so  many  seem  to  think  are 
already  answered. 

The  preceding  arguments  make  no  particular 
claim  to  novelty ;  indeed  they  have  been  floating 
more  or  less  distinctly  before  the  minds  of  geo- 
logists for  the  last  thirty  years ;  and  if,  at  the 
present  time,  it  has  seemed  desirable  to  give  them 
more  definite  and  systematic  expression,  it  is  be- 
cause palaeontology  is  every  day  assuming  a  greater 
importance,  and  now  requires  to  rest  on  a  basis 


IX  GEOLOGICAL   CONTEMPORANEITY  289 

the  firmness  of  which  is  thoroughly  well  assured. 
Among  its  fundamental  conceptions,  there  must 
be  no  confusion  between  what  is  certain  and  what 
is  more  or  less  probable.^  But,  pending  the  con- 
struction of  a  surer  foundation  than  palseontology 
now  possesses,  it  may  be  instructive,  assuming 
for  the  nonce  the  general  correctness  of  the 
ordinary  hypothesis  of  geological  contemporaneity, 
to  consider  whether  the  deductions  which  are 
ordinarily  drawn  from  the  whole  body  of  palse- 
ontological  facts  are  justifiable. 

The  evidence  on  which  such  conclusions  are 
based  is  of  two  kinds,  negative  and  positive.  The 
value  of  negative  evidence,  in  connection  with  this 
inquiry,  has  been  so  fully  and  clearly  discussed  in 
an  address  from  the  chair  of  this  Society ,2  which 
none  of  us  have  forgotten,  that  nothing  need  at 
present  be  said  about  it ;  the  more,  as  the  con- 
siderations which  have  been  laid  before  you  have 
certainly  not  tended  to  increase  your  estimation 
of  such  evidence.  It  will  be  preferable  to  turn  to 
the  positive  facts  of  palseontology,  and  to  inquire 
what  they  tell  us. 

We  are  all  accustomed  to  speak  of  the  number 
and  the  extent  of  the  changes  in  the  living  popu- 
lation of    the   globe   during  geological  time   as 


1  "  Le  plus  grand  service  qn'on  piiisse  rendre  k  la  science  est 
d'y  faire  place  nette  avant  d'y  rien  construire." — Cuvier. 

-  Anniversary  Address  for  1851,  Quart.  Joitrn.  Geol.  Soc. 
vol.  vii. 

205 


290  GEOLOGICAL  CONTEMPORANEITY  ix 

something  enormous .  and  indeed  they  are  so,  if 
we  regard  only  the  negative  differences  which 
separate  the  older  rocks  from  the  more  modem, 
and  if  we  look  upon  specific  and  generic  changes 
as  great  changes,  which  from  one  point  of  view, 
they  truly  are.  But  leaving  the  negative  differ- 
ences out  of  consideration,  and  looking  only  at  the 
positive  data  furnished  by  the  fossil  world  from  a 
broader  point  of  view — from  that  of  the  compara- 
tive anatomist  who  has  made  the  study  of  the 
greater  modifications  of  animal  form  his  chief 
business — a  surprise  of  another  kind  dawns  upon 
the  mind ;  and.  under  this  aspect  the  smallness  of 
the  total  change  becomes  as  astonishing  as  was  its 
greatness  under  the  other. 

There  are  two  hundred  known  orders  of  plants  ; 
of  these  not  one  is  certainly  known  to  exist  ex- 
clusively in  the  fossil  state.  The  whole  lapse  of 
geological  time  has  as  yet  yielded  not  a  single  new 
ordinal  type  of  vegetable  structure.^ 

The  positive  change  in  passing  from  the  recent 
to  the  ancient  animal  world  is  greater,  but  still 
sinonlarly  small.  No  fossil  animal  is  so  distinct 
from  those  now  living  as  to  require  to  be  arranged 
even  in  a  separate  class  from  those  which  contain 
existing  forms.  It  is  only  when  we  come  to  the 
orders,  which  may  be  roughly  estimated  at  about 
a  hundred  and  thirty,  that  we  meet  with  fossil 

1  See  Hooker's  Introductory  Essay  to  the  Flora  of  Tasmania^ 
p.  xxiii 


IX       GEOLOGICAL  CONTEMPORANEITY     291 

animals  so  distinct  from  those  now  living  as  to 
require  orders  for  themselves;  and  these  do  not 
amount,  on  the  most  liberal  estimate,  to  more  than 
about  10  per  cent,  of  the  whole. 

There  is  no  certainly  known  extinct  order  of 
Protozoa ;  there  is  but  one  among  the  Coelenterata 
— that  of  the  rugose  corals ;  there  is  none  among 
the  MoUusca;  there  are  three,  the  Cystidea, 
Blastoidea,  and  Edrioasterida,  among  the  Echino- 
derms;  and  two,  the  Trilobita  and  Eurypterida, 
among  the  Crustacea ;  making  altogether  five  for 
the  great  sub-kingdom  of  Annulosa.  Among 
Vertebrates  there  is  no  ordinally  distinct  fossil 
fish :  there  is  only  one  extinct  order  of  Amphibia 
— the  Labyrinthodonts ;  but  there  are  at  least  four 
distinct  orders  of  Reptilia,  viz.  the  Ichthyosauria, 
Plesiosauria,  Pterosauria,  Dinosauria,  and  perhaps 
another  or  two.  There  is  no  known  extinct  order 
of  Birds,  and  no  certainly  known  extinct  order  of 
Mammals,  the  ordinal  distinctness  of  the  "  Toxo- 
dontia  "  being  doubtful. 

The  objection  that  broad  statements  of  this 
kind,  after  all,  rest  largely  on  negative  evidence  is 
obvious,  but  it  has  less  force  than  may  at  first  be 
supposed ;  for,  as  might  be  expected  from  the  cir- 
cumstances of  the  case,  we  possess  more  abundant 
positive  evidence  regarding  Fishes  and  marine 
Mollusks  than  respecting '  any  other  forms  of 
animal  life ;  and  yet  these  offer  us,  through  the 
whole  range  of  geological  time,  no  species  ordinally 


292  GEOLOGICAL   CONTEMPORANEITY  ix 

distinct  from  those  now  living ;  while  the  far  less 
numerous  class  of  Echinoderms  presents  three,  and 
the  Crustacea  two,  such  orders,  though  none  of  these 
come  down  later  than  the  Palseozoic  age.  Lastty, 
the  Reptilia  present  the  extraordinary  and  excep- 
tional phenomenon  of  as  many  extinct  as  existing 
orders,  if  not  more ;  the  four  mentioned  maintain- 
ing their  existence  from  the  Lias  to  the  Chalk 
inclusive. 

Some  years  ago  one  of  your  Secretaries  pointed 
out  another  kind  of  positive  palaeontological 
evidence  tending  towards  the  same  conclusion — 
afforded  by  the  existence  of  what  he  termed 
"  persistent  types "  of  vegetable  and  of  animal 
life.^  He  stated,  on  the  authority  of  Dr.  Hooker, 
that  there  are  Carboniferous  plants  which  appear 
to  be  generically  identical  with  some  now  Hving  ; 
that  the  cone  of  the  Oolitic  Araiicaria  is  hardly 
distinguishable  from  that  of  an  existing  species  ; 
that  a  true  Pinus  appears  in  the  Purbecks  and  a 
Jicglans  in  the  Chalk  ;  while,  from  the  Bagshot 
Sands,  a  Banksia,  the  wood  of  which  is  not 
distinguishable  from  that  of  species  now  living 
in  Australia,  had  been  obtained. 

Turning  to  the  animal  kingdom,  he  affirmed 
the  tabulate  corals  of  the  Silurian  rocks  to  be 
wonderfully  like  those  which  now   exist;   while 

^  See  the  abstract  of  a  Lecture  "On  the  Persistent  Types  of 
Animal  Life,"  in  the  Notices  of  the  Meetings  of  the  Royal 
Institution  of  Great  Britain. — June  3,  1859,  vol.  iii.  p.  151. 


IX  GEOLOGICAL  CONTEMPORANEITY  293 

even  the  families  of  the  Aporosa  were  all  repre- 
sented in  the  older  Mesozoic  rocks. 

Among  the  Mollusca  similar  facts  were  adduced. 
Let  it  be  borne  in  mind  that  Avicula,  Mytilus^ 
Chiton,  Natica,  Patella,  Trochus,  Discina,  Orhictda^ 
Lingida,  Bhynchonella,  and  Nautilus,  all  of  which 
are  existing  genera,  are  given  without  a  doubt  as 
Silurian  in  the  last  edition  of  "  Siluria "  ;  while 
the  highest  forms  of  the  highest  Cephalopods 
are  represented  in  the  Lias  by  a  genus  Belemno^ 
teuthis,  which  presents  the  closest  relation  to  the 
existing  Loligo. 

The  two  highest  groups  of  the  Annulosa,  the 
Insecta  and  the  Arachnida,  are  represented  in  the 
Coal,  either  by  existing  genera,  or  by  forms 
differing  from  existing  genera  in  quite  minor 
peculiarities. 

Turning  to  the  Yertebrata,  the  only  palaeozoic 
Elasmobranch  Fish  of  which  we  have  any  complete 
knowledge  is  the  Devonian  and  Carboniferous 
PleuracaiitJius,  which  differs  no  more  from  existing 
Sharks  than  these  do  from  one  another. 

Again,  vast  as  is  the  number  of  undoubtedly 
Ganoid  fossil  Fishes,  and  great  as  is  their  range 
in  time,  a  large  mass  of  evidence  has  recently 
been  adduced  to  show  that  almost  all  those 
respecting  which  we  possess  sufficient  information, 
are  referable  to  the  same  sub-ordinal  groups  as 
the  existing  Lepidcstcus,  Polyptcrus,  and  Sturgeon ; 
and  that  a  singular  relation  obtains  between  the 


294  GEOLOGICAL   CONTEMPORANEITy  ix 

older  and  the  younger  Fishes ;  the  former,  the 
Devonian  Ganoids,  being  almost  all  members  of 
the  same  sub-order  as  Polypterus,  while  the 
Mesozoic  Ganoids  are  almost  all  similarly  allied 
to  Zepidosfeus} 

Again,  what  can  be  more  remarkable  than  the 
singular  constancy  of  structure  preserved  through- 
out a  vast  period  of  time  by  the  family  of  the 
Pycnodonts  and  by  that  of  the  true  Coelacanths  : 
the  former  persisting,  with  but  insignificant 
modifications,  from  the  Carboniferous  to  the 
Tertiary  rocks,  inclusive;  the  latter  existing, 
with  still  less  change,  from  the  Carboniferous 
rocks  to  the  Chalk,  inclusive  ? 

Among  Reptiles,  the  highest  living  gi'oup,  that 
of  the  Crocodilia,  is  represented,  at  the  early  part 
of  the  Mesozoic  epoch,  by  species  identical  in  the 
essential  characters  of  their  organisation  with 
those  now  living,  and  differing  from  the  latter 
only  in  such  matters  as  the  form  of  the  articular 
facets  of  the  vertebral  centra,  in  the  extent  to 
which  the  nasal  passages  are  separated  fi'om  the 
cavity  of  the  mouth  by  bone,  and  in  the  pro- 
portions of  the  limbs. 

And  even  as  regards  the  Mammalia,  the  scanty 
remains  of  Triassic  and  Oolitic  species  afford  no 
foundation  for  the  supposition  that  the  organisa- 

1  **  Memoirs  of  the  Geological  Survey  of  the  United  Kingdom. 
—Decade  x.  Preliminary  Essay  upon  the  Systematic  Arrange- 
ment of  the  Fishes  of  the  Devonian  Epoch." 


IX  GEOLOGICAL  CONTEMPORANEITY  295 

tion  of  the  oldest  forms  differed  nearly  so  much 
from  some  of  those  which  now  live  as  these  differ 
from  one  another. 

It  is  needless  to  multiply  these  instances; 
enough  has  been  said  to  justify  the  statement 
that,  in  view  of  the  immense  diversity  of  known 
animal  and  vegetable  forms,  and  the  enormous 
lapse  of  time  indicated  by  the  accumulation  of 
fossiliferous  strata,  the  only  circumstance  to  be 
wondered  at  is,  not  that  the  changes  of  Hfe,  as 
exhibited  by  positive  evidence,  have  been  so  gi'eat, 
but  that  they  have  been  so  small. 

Be  they  great  or  small,  however,  it  is  desirable 
to  attempt  to  estimate  them.  Let  us,  therefore, 
take  each  great  division  of  the  animal  world  in 
succession,  and,  whenever  an  order  or  a  family  can 
be  shown  to  have  had  a  prolonged  existence,  let  us 
endeavour  to  ascertain  how  far  the  later  members 
of  the  group  differ  from  the  earlier  ones.  If  these 
later  members,  in  all  or  in  many  cases,  exhibit  a 
certain  amount  of  modification,  the  fact  is,  so  far, 
evidence  in  favour  of  a  general  law  of  change ; 
and,  in  a  rough  way,  the  rapidity  of  that  change 
will  be  measured  by  the  demonstrable  amount  of 
modification.  On  the  other  hand,  it  must  be 
recollected  that  the  absence  of  any  modification, 
while  it  may  leave  the  doctrine  of  the  existence  of 
a  law  of  change  without  positive  support,  cannot 
possibly  disprove  all  forms  of  that  doctrine,  though 


29G  GEOLOGICAL   CONTEMPORANEITY  ix 

it  may  afiford  a  sufficient  refutation  of  many  of 
them. 

The  Protozoa. — The  Protozoa  are  represented 
throughout  the  whole  range  of  geological  series, 
from  the  Lower  Silurian  formation  to  the  present 
day.  The  most  ancient  forms  recently  made 
known  hy  Ehrenberg  are  exceedingly  like  those 
which  now  exist :  no  one  has  ever  pretended  that 
the  difference  between  any  ancient  and  any  modern 
Foraminifera  is  of  more  than  generic  value,  nor 
are  the  oldest  Foraminifera  either  simpler,  more 
embryonic,  or  less  differentiated,  than  the  existing 
forms. 

The  Ccelenterata. — The  Tabulate  Corals  have 
existed  from  the  Silurian  epoch  to  the  present 
day,  but  I  am  not  aware  that  the  ancient  Hcliolitcs 
possesses  a  single  mark  of  a  more  embryonic  or 
less  differentiated  character,  or  less  high  organisa- 
tion, than  the  existing  Helicpora.  As  for  the 
Aporose  Corals,  in  what  respect  is  the  Silurian 
FalceGcyclus  less  highly  organised  or  more  embry- 
onic than  the  modern  Fungia,  or  the  Liassic 
Aporosa  than  the  existing  members  of  the  same 
families  ? 

The  Mollusca. — In  what  sense  is  the  living 
Waldheimia  less  embryonic,  or  more  specialised, 
than  the  palaeozoic  B^irifer ;  or  the  existing 
Bhynchonellce,  Cranioe,  Fiscince,  Lingulce,  than  the 
Silurian  species  of  the  same  genera  ?  In  what 
sense  can  Loligo  or  Sjoinda  be  said  to  be  more 


IX  GEOLOGICAL   CONTEMPOEANEITY  297 

specialised,  or  less  embryonic,  than  Belcmnites ; 
or  the  modern  species  of  Lamelhbranch  and 
Gasteropod  genera,  than  the  Silurian  species  of 
the  same  genera  ? 

The  Annulosa. — The  Carboniferous  Insecta 
and  Arachnida  are  neither  less  specialised,  nor 
more  embryonic,  than  these  that  now  live,  nor  are 
the  Liassic  Cnripedia  and  Macrura ;  while  several 
of  the  Brachyura,  which  appear  in  the  Chalk, 
belong  to  existing  genera;  and  none  exhibit 
either  an  intermediate,  or  an  embryonic, 
character. 

The  Vertebrata. — Among  fishes  I  have 
referred  to  the  Coelacanthuii  (comprising  the 
genera  Gmlacanthus,  HolopJiagus,  Undina,  and 
Macropoma)  as  affording  an  example  of  a  persistent 
type ;  and  it  is  most  remarkable  to  note  the 
smallness  of  the  differences  between  any  of  these 
fishes  (affecting  at  most  the  proportions  of  the 
body  and  fins,  and  the  character  and  sculpture 
of  the  scales),  notwithstanding  their  enormous 
range  in  time.  In  ail  the  essentials  of  its 
very  peculiar  structure,  the  Macropoma  of  the 
Chalk  is  identical  with  the  Cmlacanthus  of  the 
Coal.  Look  at  the  genus  Lepidotus,  again,  per- 
sisting without  a  modification  of  importance 
from  the  Liassic  to  the  Eocene  formations  in- 
clusivly. 

Or  among  the  Teleostei — in  what  respect  is 
the    Beryx   of    the   Chalk    more    embryonic,   or 


298  GEOLOGICAL  CONTEMPORANEITY  ix 

less  differentiated,  than  Beryx  lincatus  of  King 
George's  Sound  ? 

Or  to  turn  to  the  higher  Vertebrata — in  what 
sense  are  the  Liassic  Chelonia  inferior  to  those 
which  now  exist  ?  How  are  the  Cretaceous 
Ichthyosauria,  Plesiosauria,  or  Pterosauria  less 
embryonic,  or  more  differentiated,  species  than 
those  of  the  Lias  ? 

Or  lastly,  in  what  circumstance  is  the  PJiasco- 
lotherium  more  embryonic,  or  of  a  more  genera- 
lised type,  than  the  modern  Opossum;  or  a 
ZoijhiGdoi,  or  a  Fala3othermmj  than  a  modern 
Taijirus  or  Hyrax'^ 

These  examples  might  be  almost  indefinitely 
multiplied,  but  surely  they  are  sufficient  to  prove 
that  the  only  safe  and  unquestionable  testimony 
we  can  procure — positive  evidence — fails  to  dem- 
onstrate any  sort  of  progressive  modification 
towards  a  less  embryonic,  or  less  generahsed,  type 
in  a  great  many  groups  of  animals  of  long- 
continued  geological  existence.  In  these  groups 
there  is  abundant  evidence  of  variation — none  of 
what  is  ordinarily  understood  as  progression ;  and, 
if  the  known  geological  record  is  to  be  regarded 
as  even  any  considerable  fragment  of  the  whole, 
it  is  inconceivable  that  any  theory  of  a  necessarily 
progressive  development  can  stand,  for  the  numer- 
ous orders  and  families  cited  afford  no  trace  of 
such  a  process. 

But  it  is  a  most  remarkable  fact,  that,  while  the 


IX 


GEOLOGICAL   CONTEMPORANEITY  299 


groups  which  have  been  mentioned,  and  many 
besides,  exhibit  no  sign  of  progressive  modification, 
there  are  others,  co-existing  with  them,  under  the 
same  conditions,  in  which  more  or  less  distinct 
indications  of  such  a  process  seems  to  be  traceable. 
Among  such  indications  I  may  remind  you  of  the 
predominance  of  Holostome  Gasteropoda  in  the 
older  rocks  as  compared  with  that  of  Siphonostone 
Gasteropoda  in  the  later.  A  case  less  open  to  the 
objection  of  negative  evidence,  however,  is  that 
afforded  by  the  Tetrabranchiate  Cephalopoda,  the 
forms  of  the  shells  and  of  the  septal  sutures 
exhibiting  a  certain  increase  of  complexity  in  the 
newer  genera.  Here,  however,  one  is  met  at  once 
with  the  occurrence  of  Orthoceras  and  Baculites  at 
the  two  ends  of  the  series,  and  of  the  fact  that 
one  of  the  simplest  genera.  Nautilus^  is  that 
which  now  exists. 

The  Crinoidea,  in  the  abundance  of  stalked 
forms  in  the  ancient  formations  as  compared  with 
their  present  rarity,  seem  to  present  us  with  a 
fair  case  of  modification  from  a  more  embryonic 
towards  a  less  embryonic  condition.  But  then,  on 
careful  consideration  of  the  facts,  the  objection 
arises  that  the  stalk,  caljrx,  and  arms  of  the  palae- 
ozoic Crinoid  are  exceedingly  different  from  the 
corresponding  organs  of  a  larval  Comahda  ;  and  it 
might  with  perfect  justice  be  argued  that  Actino- 
crinus  and  Eucalyptccrinus,  for  example,  depart  to 
the  full  as  widely,  in  one  direction,  from  the  stalked 


800  GEOLOGICAL   CONTEMPORANEITY  jx 

embryo  of  Comahda,  as  Comatula  itself  does  in 
the  other. 

The  Echinidea,  again,  are  frequently  quoted  as 
exhibiting  a  gradual  passage  from  a  more  genera- 
lised to  a  more  specialised  type,  seeing  that  the 
elongated,  or  oval,  Spatangoids  appear  after  the 
spheroidal  Echinoids.  But  here  it  might  be 
argued,  on  the  other  hand,  that  the  spheroidal 
Echinoids,  in  reality,  depart  further  from  the 
general  plan  and  from  the  embryonic  form  than 
the  elongated  Spatangoids  do ;  and  that  the 
peculiar  dental  apparatus  and  the  pedicellarige  of 
the  former  are  marks  of  at  least  as  great  differ- 
entiation as  the  petaloid  ambulacra  and  semitse  of 
the  latter. 

Once  more,  the  prevalence  of  Macrurous  before 
Brachyurous  Podophthalmia  is,  apparently,  a  fair 
piece  of  evidence  in  favour  of  progressive  modifi- 
cation in  the  same  order  of  Crustacea;  and  yet 
the  case  will  not  stand  much  sifting,  seeing  that 
the  Macrurous  Podophthalmia  depart  as  far  in  one 
direction  from  the  common  type  of  Podophthalmia, 
or  from  any  embryonic  condition  of  the  Brachjoira, 
as  the  Brachyura  do  in  the  other ;  and  that  the 
middle  terms  between  Macrura  and  Brachyura — 
the  Anomura — are  little  better  represented  in  the 
older  Mesozoic  rocks  than  the  Brachyura  are. 

None  of  the  cases  of  progressive  modification 
which  are  cited  from  among  the  Invertebrata 
appear  to  me  to  have  a  foundation  less  open  to 


IX       GEOLOGICAL  CONTEMPORANEITY     3Ul 

criticism  than  these ;  and  if  this  be  so,  no  careful 
reasoner  would,  I  think,  be  inclined  to  lay  very 
great  stress  upon  them.  Among  the  Vertebrata, 
however,  there  are  a  few  examples  which  appear  to 
be  far  less  open  to  objection. 

It  is,  in  fact,  true  of  several  groups  of  Verte- 
brata which  have  lived  through  a  considerable 
range  of  time,  that  the  endoskeleton  (more  par- 
ticularly the  spinal  column)  of  the  older  genera 
presents  a  less  ossified,  and,  so  far,  less  differ- 
entiated, condition  than  that  of  the  younger 
genera.  Thus  the  Devonian  Ganoids,  though 
almost  all  members  of  the  same  sub-order  as 
Polypterus,  and  presenting  numerous  important  re- 
semblances to  the  existing  genus,  which  possesses 
biconclave  vertebrae,  are,  for  the  most  part,  wholly 
devoid  of  ossified  vertebral  centra.  The  Mesozoic 
Lepidosteidse,  again,  have,  at  most,  biconcave 
vertebrae,  while  the  existing  Lepidosteus  has 
Salamandroid,  opisthocoelous,  vertebrae.  So,  none 
of  the  Palaeozoic  Sharks  have  shown  themselves 
to  be  possessed  of  ossified  vertebrae,  while  the 
majority  of  modern  Sharks  possess  such  vertebrae. 
Again,  the  more  ancient  Crocodilia  and  Lacertilia 
have  vertebrae  with  the  articular  facets  of  their 
centra  flattened  or  biconcave,  while  the  modern 
members  of  the  same  group  have  them  procoelous. 
But  the  most  remarkable  examples  of  progressive 
modification  of  the  vertebral  column,  in  corre- 
spondence with  geological  age,  are  those  afforded 


302  GEOLOGICAL   CONTEMPORANEITY  m 

by  the  Pycnodonts  among  fish,  and  the  Labyrin- 
thodonts  among  Amphibia. 

The  late  able  ichthyologist  Heckel  pointed  out 
the  fact,  that,  while  the  Pycnodonts  never  possess 
true  vertebral  centra,  they  differ  in  the  degi^ee  of 
expansion  and  extension  of  the  ends  of  the  bony 
arches  of  the  vertebrae  upon  the  sheath  of  the 
notochord ;  the  Carboniferous  forms  exhibiting 
hardly  any  such  expansion,  while  the  Mesozoic 
genera  present  a  greater  and  greater  development, 
until,  in  the  Tertiary  forms,  the  expanded  ends 
become  suturally  united  so  as  to  form  a  sort  of 
false  vertebra.  Hermann  von  Meyer,  again,  to 
whose  luminous  researches  we  are  indebted  for 
our  present  large  knowledge  of  the  organisation  of 
the  older  Labyrinthodonts,  has  proved  that  the 
Carboniferous  Archegosaurus  had  very  imperfectly 
developed  vertebral  centra,  while  the  Triassic 
Mastodonsaurus  had  the  same  parts  completely 
ossified.^ 

The  regularity  and  evenness  of  the  dentition  of 
the  Ano2)Iotherium,  as  contrasted  with  that  of  exist- 
in  o-  Artiodactyles,  and  the  assumed  nearer  approach 
of  the  dentition  of  certain  ancient  Carnivores  to 
the  typical  arrangement,  have  also  been  cited  as 
exemplifications  of  a  law  of  progressive  develop- 
ment, but   I  know  of  no  other  cases   Based   on 

^  As  this  Address  is  passing  through  the  press  (March  7, 
1862),  evidence  lies  before  me  of  the  existence  of  a  new  Laby- 
rinthodont  {Pholvh'jnstrr),  from  the  Edinburgh  coal-field  with 
well-ossified  vertebral  centra. 


IX  GEOLOGICAL  CONTEMPORANEITY  803 

positive  evidence  which  are  worthy  of  particular 
notice. 

What  then  does  an  impartial  survey  of  the 
positively  ascertained  truths  of  palaeontology  testify 
in  relation  to  the  common  doctrines  of  progressive 
modification,  which  suppose  that  modification  to 
have  taken  place  by  a  necessary  progress  from 
more  to  less  embryonic  forms,  or  from  more  to 
less  generalised  types,  within  the  limits  of  the 
period  represented  by  the  fossiliferous  rocks  ? 

It  negatives  those  doctrines ;  for  it  either 
shows  us  no  evidence  of  any  such  modification,  or 
demonstrates  it  to  have  been  very  slight ;  and  as 
to  the  nature  of  that  modification,  it  yields  no 
evidence  whatsoever  that  the  earlier  members  of 
any  long-continued  group  were  more  generalised 
in  structure  than  the  later  ones.  To  a  certain 
extent,  indeed,  it  may  be  said  that  imperfect 
ossification  of  the  vertebral  column  is  an  em- 
bryonic character;  but,  on  the  other  hand,  it 
would  be  extremely  incorrect  to  suppose  that  the 
vertebral  columns  of  the  older  Yertebrata  are  in 
any  sense  embryonic  in  their  whole  structure. 

Obviously,  if  the  earliest  fossiliferous  rocks  now 
known  are  coeval  with  the  commencement  of  life, 
and  if  their  contents  give  us  any  just  conception 
of  the  nature  and  the  extent  of  the  earliest  fauna 
and  flora,  the  insignificant  amount  of  modification 
which  can  be  demonstrated  to  have  taken  place  in 
any  one  group  of  animals,  or  plants,  is  quite  in- 


304  GEOLOGICAL   CONTEMPORANEITY  ix 

compatible  with  the  hypothesis  that  all  living 
forms  are  the  results  of  a  necessary  process  of 
progressive  development,  entirely  comprised  within 
the  time  represented  by  the  fossiliferous  rocks. 

Contrariwise,  any  admissible  hypothesis  of  pro- 
gressive modification  must  be  compatible  with 
persistence  without  progression,  through  indefi- 
nite periods.  And  should  such  an  hypothesis 
eventually  be  proved  to  be  true,  in  the  only 
way  in  which  it  can  be  demonstrated,  viz. 
by  observation  and  experiment  upon  the 
existing  forms  of  life,  the  conclusion  will 
inevitably  present  itself,  that  the  Palaeozoic 
Mesozoic,  and  Cainozoic  faunae  and  florae,  taken 
together,  bear  somewhat  the  same  proportion  to 
the  whole  series  of  living  beings  which  have 
occupied  this  globe,  as  the  existing  fauna  and 
flora  do  to  them. 

Such  are  the  results  of  palaeontology  as  they 
appear,  and  have  for  some  years  appeared,  to  the 
mind  of  an  inquirer  who  regards  that  study  simply 
as  one  of  the  applications  of  the  great  biological 
sciences,  and  who  desires  to  see  it  placed  upon  the 
same  sound  basis  as  other  branches  of  physical 
inquiry.  If  the  arguments  which  have  been 
brought  forward  are  valid,  probably  no  one,  in  view 
of  the  present  state  of  opinion,  will  be  inclined  to 
think  the  time  wasted  which  has  been  spent  upon 
their  elaboration. 


X 

GEOLOGICAL  REFORM 

[1869] 

•'  A  great  reform  in  geological  speculation  seems  now  to  ha'/e 
become  necessary." 

"  It  is  quite  certain  that  a  great  mistake  has  been  made— that 
British  popular  geology  at  the  present  time  is  in  direct  opposi- 
tion to  the  principles  of  Natural  Philosopliy."  ^ 

In  reviewing  the  course  of  geological  thought 
during  the  past  year,  for  the  purpose  of  discovering 
those  matters  to  which  I  might  most  fitly  direct 
your  attention  in  the  Address  which  it  now 
becomes  my  duty  to  deliver  from  the  Presidential 
Chair,  the  two  somewhat  alarming  sentences 
which  I  have  just  read,  and  which  occur  in  an 
able  and  interesting  essay  by  an  eminent  natural 
philosopher,  rose  into  such  prominence  before  my 
mind  that  they  eclijDsed  everything  else. 

It  surely  is  a  matter  of  paramount  importance 

1  On  Geological  Time.  By  Sir  W.  Thomson,  LL.D.  Trans* 
actions  of  the  Geological  Society  of  Glasgow,  vol.  iii. 

206 


306  GEOLOGICAL  REFORM  X 

for  the  British  geologists  (some  of  them  very 
popular  geologists  too)  here  in  solemn  annual 
session  assembled,  to  inquire  whether  the  severe 
judgment  thus  passed  upon  them  by  so  high  an 
authority  as  Sir  William  Thomson  is  one  to  which 
they  must  plead  guilty  sans  phrase,  or  whether 
they  are  prepared  to  say  "  not  gnilty/'  and  appeal 
for  a  reversal  of  the  sentence  to  that  higher 
court  of  educated  scientific  opinion  to  which  we 
are  all  amenable. 

As  your  attorney-general  for  the  time  being, 
I  thought  I  could  not  do  better  than  get  up  the 
case  with  a  view  of  advising  you.  It  is  true  that 
the  charges  brought  forward  by  the  other  side 
involve  the  consideration  of  matters  quite  foreign 
to  the  pursuits  with  w^hich  I  am  ordinarily  occu- 
pied ;  but,  in  that  respect,  I  am  only  in  the 
position  which  is,  nine  times  out  of  ten,  occupied 
by  counsel,  who  nevertheless  contrive  to  gain 
their  causes,  mainly  by  force  of  mother- wit  and 
common-sense,  aided  by  some  training  in  other 
intellectual  exercises. 

Nerved  by  such  precedents,  I  proceed  to  put 
my  pleading  before  you. 

And  the  first  question  with  w^hich  I  propose  to 
deal  is,  What  is  it  to  which  Sir  W.  Thomson 
refers  when  he  speaks  of  "  geological  speculation  " 
and  "  British  popular  geology  "  ? 

I  find  three,  more  or  less  contradictory,  systems 
of  geological  thought,  each  of  which  might  fairly 


X  GEOLOGICAL   REFORM  307 

enough  claim  these  appellations,  standing  side  by 
side  in  Britain.  I  shall  call  one  of  them  Cata- 
STROPHISM,  another  UNiFORMiTARiANlSM,the  third 
Evolutionism  ;  and  I  shall  try  briefly  to  sketch 
the  characters  of  each,  that  you  may  say  whether 
the  classification  is,  or  is  not,  exhaustive. 

By  Catastrophism,  I  mean  any  form  of  geo- 
logical speculation  which,  in  order  to  account  for 
the  phenomena  of  geology,  supposes  the  operation 
of  forces  different  in  their  nature,  or  immeasur- 
ably different  in  power,  from  those  which  we  at 
present  see  in  action  in  the  universe. 

The  Mosaic  cosmogony  is,  in  this  sense,  cata- 
strophic, because  it  assumes  the  operation  of 
extra-natural  power.  The  doctrine  of  violent 
upheavals,  d^hddcs,  and  cataclysms  in  general,  is 
catastrophic,  so  far  as  it  assumes  that  these  were 
brought  about  by  causes  which  have  now  no 
parallel.  There  was  a  time  when  catastrophism 
might,  pre-eminently,  have  claimed  the  title  of 
"  British  popular  geology  "  ;  and  assuredly  it  has 
yet  many  adherents,  and  reckons  among  its  sup- 
porters some  of  the  most  honoured  members  of 
this  Society. 

By  Uniformitarianism,  I  mean  especially,  the 
teaching  of  Hutton  and  of  Lyell. 

That  gi^eat  though  incomplete  work,  "  The 
Theory  of  the  Earth,"  seems  to  me  to  be  one  of 
the  most  remarkable  contributions  to  geology 
which  is  recorded  in  the  annals  of  the  science. 


308  GEOLOGICAL  REFORM  X 

So  far  as  the  not-living  world  is  concerned,  uni- 
formitarianism  lies  there,  not  only  in  germ,  but  in 
blossom  and  fruit. 

If  one  asks  how  it  is  that  Hutton  was  led 
to  entertain  views  so  far  in  advance  of  those 
prevalent  in  his  time,  in  some  respects  ;  while,  in 
others,  they  seem  almost  curiously  Hmited,  the 
answer  appears  to  me  to  be  plain. 

Hutton  was  in  advance  of  the  geological  specu- 
lation of  his  time,  because,  in  the  first  place,  he 
had  amassed  a  vast  store  of  knowledge  of  the 
facts  of  geology,  gathered  by  personal  observation 
in  travels  of  considerable  extent ;  and  because,  in 
the  second  place,  he  was  thoroughly  trained  in 
the  physical  and  chemical  science  of  his  day,  and 
thus  possessed,  as  much  as  any  one  in  his  time 
could  possess  it,  the  knowledge  which  is  requisite 
for  the  just  interpretation  of  geological  pheno- 
mena, and  the  habit  of  thought  which  fits  a  man 
for  scientific  inquiry. 

It  is  to  this  thorough  scientific  training  that  I 
ascribe  Hutton's  steady  and  persistent  refusal  to 
look  to  other  causes  than  those  now  in  operation, 
for  the  explanation  of  geological  phenomena. 

Thus  he  writes  : — "  I  do  not  pretend,  as  he 
[M.  de  Luc]  does  in  his  theory,  to  describe  the 
beginning  of  things.  I  take  things  such  as  I  find 
them  at  present ;  and  from  these  I  reason  with 
regard  to  that  which  must  have  been."  ^ 

1  The  Theory  of  the  Earth,  vol.  i.  p.  173,  note. 


X  GEOLOGICAL   REFORM  809 

And  again : — "  A  theory  of  the  earth,  which 
has  for  object  truth,  can  have  no  retrospect  to 
that  which  had  preceded  the  present  order  of  the 
world ;  for  this  order  alone  is  what  we  have  to 
reason  upon ;  and  to  reason  without  data  is 
nothing  but  delusion.  A  theory,  therefore,  which 
is  limited  to  the  actual  constitution  of  this  earth 
cannot  be  allowed  to  proceed  one  step  beyond  the 
present  order  of  things."  ^ 

And  so  clear  is  he,  that  no  causes  beside  such 
as  are  now  in  operation  are  needed  to  account  for 
the  character  and  disposition  of  the  components 
of  the  crust  of  the  earth,  that  he  says,  broadly 
and  boldly: — ^*  .  .  .  There  is  no  part  of  the 
earth  which  has  not  had  the  same  origin,  so 
far  as  this  consists  in  that  earth  being  collected 
at  the  bottom  of  the  sea,  and  afterwards  pro- 
duced, as  land,  along  with  masses  of  melted 
substances,  by  the  operation  of  mineral  causes."  ^ 

But  other  influences  were  at  work  upon  Hutton 
beside  those  of  a  mind  logical  by  nature,  and 
scientific  by  sound  training;  and  the  pecuHar 
turn  which  his  speculations  took  seems  to  me 
to  be  unintelligible,  unless  these  be  taken  into 
account.  The  arguments  of  the  French  astro- 
nomers and  mathematicians,  which,  at  the  end 
of  the  last  century,  were  held  to  demonstrate 
the  existence  of  a  compensating  arrangement 
among  the  celestial  bodies,  whereby  all  perturba- 

1   The  Theory  of  the  EartJi,  vol.  i.  p.  281.  -  Ibid.  p.  3/1. 


810  GEOLOGICAL   REFORM  X 

tions  eventually  reduced  themselves  to  oscilla- 
tions on  each  side  of  a  mean  position,  and  the 
stability  of  the  solar  system  was  secured,  had 
evidently  taken  strong  hold  of  Hutton's  mind. 

In  those  oddly  constructed  periods  which  seem 
to  have  prejudiced  many  persons  against  reading 
his  works,  but  which  are  full  of  that  peculiar,  if 
unattractive,  eloquence  which  flows  from  mastery 
of  the  subject,  Hutton  says  : — 

"  We  have  now  got  to  the  end  of  our  reasoning  ; 
we  have  no  data  further  to  conclude  immediately 
from  that  which  actually  is.  But  we  have  got 
enough;  we  have  the  satisfaction  to  find,  that 
in  Nature  there  is  wisdom,  system,  and  consist- 
ency. For  having,  in  the  natural  history  of  this 
earth,  seen  a  succession  of  worlds,  we  may  from 
this  conclude  that  there  is  a  system  in  Nature ; 
in  like  manner  as,  from  seeing  revolutions  of  the 
planets,  it  is  concluded,  that  there  is  a  system  by 
which  they  are  intended  to  continue  those  revolu- 
tions. But  if  the  succession  of  worlds  is  estab- 
lished in  the  system  of  nature,  it  is  in  vain  to 
look  for  anything  higher  in  the  origin  of  the 
earth.  The  result,  therefore,  of  this  physical 
inquiry  is,  that  we  find  no  vestige  of  a  beginning, 
— no  prospect  of  an  end."  ^ 

Yet  another  influence  worked  strongly  upon 
Hutton.  Like  most  philosophers  of  his  age,  he 
coquetted  with  those  final  causes  which  have 
»  The  Theory  of  the  Earth,  vol.  i.  p.  200. 


X  GEOLOGICAL   REFORM  311 

been  named  barren  virgins,  but  which  might 
be  more  fitly  termed  the  hetairce  of  philosophy, 
so  constantly  have  they  led  men  astray.  The 
final  cause  of  the  existence  of  the  world  is,  for 
Hutton,  the  production  of  life  and  intelligence. 
"We  have  now  considered  the  globe  of  this 
earth  as  a  machine,  constructed  upon  chemical 
as  well  as  mechanical  principles,  by  which  its 
different  parts  are  all  adapted,  in  form,  in  quality, 
and  in  quantity,  to  a  certain  end ;  an  end  at- 
tained with  certainty  or  success ;  and  an  end 
from  which  we  may  perceive  wisdom,  in  contem- 
plating the  means  employed. 

"  But  is  this  world  to  be  considered  thus 
merely  as  a  machine,  to  last  no  longer  than  its 
parts  retain  their  present  position,  their  proper 
forms  and  qualities  ?  Or  may  it  not  be  also 
considered  as  an  organised  body?  such  as  has 
a  constitution  in  which  the  necessary  decay  of 
the  machine  is  naturally  repaired,  in  the  exertion 
of  those  productive  powers  by  which  it  had 
been  formed. 

"  This  is  the  view  in  which  we  are  now  to 
examine  the  globe  ;  to  see  if  there  be,  in  the 
constitution  of  this  world,  a  reproductive  opera- 
tion, by  which  a  ruined  constitution  may  be 
again  repaired,  and  a  duration  or  stability  thus 
procured  to  the  machine,  considered  as  a  world 
sustaining  plants  and  animals."^ 

»  Th^  Theory  of  the  Earth,  vol.  i.  pp.  16,  17. 


312  GEOLOGICAL   REFORM  X 

Kirwan,  and  the  other  Philistines  of  the  day, 
accused  Hutton  of  declaring  that  his  theory 
implied  that  the  world  never  had  a  beginning, 
and  never  differed  in  condition  from  its  present 
state.  Nothing  could  be  more  gi'ossly  unjust,  as 
he  expressly  guards  himself  against  any  such 
conclusion  in  the  following  terms  : — ■ 

"  But  in  thus  tracing  back  the  natural  opera- 
tions which  have  succeeded  each  other,  and  mark 
to  us  the  course  of  time  past,  we  come  to  a  period 
in  which  we  cannot  see  any  farther.  This,  how- 
ever, is  not  the  beginning  of  the  operations  which 
proceed  in  time  and  according  to  the  wise 
economy  of  this  world  ;  nor  is  it  the  establishing 
of  that  which,  in  the  course  of  time,  had  no 
beginning;  it  is  only  the  hmit  of  our  retrospec- 
tive view  of  those  operations  which  have  come 
to  pass  in  time,  and  have  been  conducted  by 
supreme  intelligence."  ^ 

I  have  spoken  of  Uniformitarianism  as  the  doc- 
trine of  Hutton  and  of  Lyell.  If  I  have  quoted 
the  older  wi^iter  rather  than  the  newer,  it  is  be- 
cause his  works  are  little  known,  and  his  claims 
on  our  veneration  too  frequently  forgotten,  not 
because  I  desire  to  dim  the  fame  of  his  eminent 
successor.  Few  of  the  present  generation  of 
geologists  have  read  Playfair's  "  Illustrations," 
fewer  still  the  original "  Theory  of  the  Earth  "  ;  the 
more  is  the  pity ;  but  which  of  us  has  not  thumbed 

1  The  Theory  of  the  Earth,  vol.  i.  p.  223. 


X  GEOLOGICAL   REFORM  313 

every  page  of  the  "  Principles  of  Geology "  ?  I 
think  that  he  who  writes  fairly  the  history  of  his 
own  progress  in  geological  thought,  will  not  be 
able  to  separate  his  debt  to  Hutton  from  his 
obligations  to  Lyell ;  and  the  history  of  the  pro- 
gress of  individual  geologists  is   the   history   of 


No  one  can  doubt  that  the  influence  of  uniform- 
itarian  views  has  been  enormous,  and,  in  the 
main,  most  beneficial  and  favourable  to  the 
progress  of  sound  geology. 

Nor  can  it  be  questioned  that  Uniformitarianism 
has  even  a  stronger  title  than  Catastrophism  to 
call  itself  the  geological  speculation  of  Britain,  or, 
if  you  will,  British  popular  geology.  For  it  is 
eminently  a  British  doctrine,  and  has  even  now 
made  comparatively  little  progress  on  the  con- 
tinent of  Europe.  Nevertheless,  it  seems  to  me 
to  be  open  to  serious  criticism  upon  one  of  its 
aspects. 

I  have  sho"v\Ti  how  unjust  was  the  insinuation 
that  Hutton  denied  a  beginning  to  the  world. 
But  it  would  not  be  unjust  to  say  that  he  persist- 
ently in  practice,  shut  his  eyes  to  the  existence 
of  that  prior  and  different  state  of  things  which, 
in  theory,  he  admitted ;  and,  in  this  aversion  to 
look  beyond  the  veil  of  stratified  rocks,  Lyell 
follows  him. 

Hutton  and  Lyell  alike  agree  in  their  indis- 
position to  carry  their  speculations  a  step  beyond 


814  GEOLOGICAL  REFORM  X 

the  period  recorded  in  the  most  ancient  strata 
now  open  to  observation  in  the  crust  of  the  earth. 
This  is,  for  Hutton,  "  the  point  in  which  we  can- 
not see  any  farther  "  ;  while  Lyell  tells  us, — 

"  The  astronomer  may  find  good  reasons  for 
ascribing  the  earth's  form  to  the  original  fluidity 
of  the  mass,  in  times  long  antecedent  to  the  first 
introduction  of  living  beings  into  the  planet ;  but 
the  geologist  must  be  content  to  regard  the  earliest 
monuments  which  it  is  his  task  to  interpret,  as 
belonging  to  a  period  when  the  crust  had  already 
acquired  great  solidity  and  thickness,  probably  as 
great  as  it  now  possesses,  and  when  volcanic  rocks, 
not  essentially  differing  from  those  now  produced, 
were  formed  from  time  to  time,  the  intensity  of 
volcanic  heat  being  neither  greater  nor  less  than 
it  is  now."  ^ 

And  again,  "  As  geologists,  we  learn  that  it  is 
not  only  the  present  condition  of  the  globe  which 
has  been  suited  to  the  accommodation  of  myriads 
of  living  creatures,  but  that  many  former  states 
also  have  been  adapted  to  the  organisation  and 
habits  of  prior  races  of  beings.  The  disposition  of 
the  seas,  continents  and  islands,  and  the  climates, 
have  varied ;  the  species  likewise  have  been 
changed  ;  and  yet  they  have  all  been  so  modelled, 
on  types  analogous  to  those  of  existing  plants  and 
animals,  as  to  indicate,  throughout,  a  perfect 
harmony  of  design  and  unity  of  purpose.  To 
*  Principles  of  Geology,  vol.  ii.  p.  211. 


X  (GEOLOGICAL   REFORM  315 

assume  that  the  evidence  of  the  beginning,  or  end, 
of  so  vast  a  scheme  lies  within  the  reach  of  our 
philosophical  inquiries,  or  even  of  our  speculations, 
appears  to  be  inconsistent  with  a  just  estimate  of 
the  relations  which  subsist  between  the  finite 
powers  of  man  and  the  attributes  of  an  infinite 
and  eternal  Being."  ^ 

The  limitations  implied  in  these  passages  appear 
to  me  to  constitute  the  weakness  and  the  logical 
defect  of  Uniformitarianism.  No  one  will  impute 
blame  to  Hutton  that,  in  face  of  the  imperfect 
condition,  in  his  day,  of  those  physical  sciences 
which  furnish  the  keys  to  the  riddles  of  geology, 
he  should  have  thought  it  practical  wisdom  to 
limit  his  theory  to  an  attempt  to  account  for  "  the 
present  order  of  things  "  ;  but  I  am  at  a  loss  to 
comprehend  why,  for  all  time,  the  geologist  must 
be  content  to  regard  the  oldest  fossiiiferous  rocks 
as  the  ultima  Thide  of  his  science  ;  or  what  there 
is  inconsistent  with  the  relations  between  the 
finite  and  the  infinite  mind,  in  the  assumption, 
that  we  may  discern  somewhat  of  the  beginning, 
or  of  the  end,  of  this  speck  in  space  we  call  our 
earth.  The  finite  mind  is  certainly  competent  to 
trace  out  the  development  of  the  fowl  within  the 
Qgg ;  and  I  know  not  on  what  ground  it  should 
find  more  difficulty  in  unravelling  the  complexities 
of  the  development  of  the  earth.     In  fact,  as  Kant 

^  Princijjles  of  Geology,  vol.  ii.  p.  613. 


316  GEOLOGICAL   REFORM  X 

has  well  remarked,^  the  cosmical  process  is  really 
simpler  than  the  biological. 

This  attempt  to  limit,  at  a  particular  point,  the 
progress  of  inductive  and  deductive  reasoning 
from  the  things  which  are,  to  those  which  were — 
this  faithlessness  to  its  own  logic,  seems  to  me  to 
have  cost  Uniformitarianism  the  place,  as  the 
j)ermanent  form  of  geological  speculation,  which 
it  might  otherwise  have  held. 

It  remains  that  I  should  put  before  you  what 
I  understand  to  be  the  third  phase  of  geological 
speculation — namely,  Evolutionism. 

I  shall  not  make  what  I  have  to  say  on  this 
head  clear,  unless  I  divero^e,  or  seem  to  divero^e,  for  a 
while,  from  the  direct  path  of  my  discourse,  so  far 
r.s  to  explain  what  I  take  to  be  the  scope  of  geology 
itself  I  conceive  geology  to  be  the  history  of  the 
earth,  in  precisely  the  same  sense  as  biology  is 
the  history  of  living  beings ;  and  I  trust  you  will 
not  think  that  I  am  overpowered  by  the  influence 
of  a  dominant  pursuit  if  I  say  that  I  trace  a  close 
analogy  between  these  two  histories. 

If  I  study  a  living  being,  under  what  heads 
does  the  knowledge  I  obtain  fall  ?  I  can  learn  its 
structure,  or  what  we  call  its  Anatomy  ;  and  its 

^  "Mandarfes  sicli  also  nicht  befremden  lassen,  wenn  ich 
mich  unterstehe  zu  sacfen,  dass  elier  die  Bildung  aller  Plimmels- 
korper,  die  Ursache  ihrer  Bewegungen,  knrz  der  Ursprnng  der 
ganzen  gegenwriitigen  Verfassimg  des  Weltbaiies  werdenkonnen 
eingeseheii  wevden,  elie  die  Erzengung  eines  einzigen  Kiautes  odei 
einer  Raiij^eans  rnechanischon  Gniiideri,  dcutlichuud  voDstandig 
kund  vverden  wird." — Kant's  iSdmmdiche  Werke,  Bd,  i.  p.  220. 


X  GEOLOGICAL   REFORM  317 

Development,  or  the  series  of  changes  which  it 
passes  through  to  acquire  its  complete  structure. 
Then  I  find  that  the  living  being  has  certain 
powers  resulting  from  its  own  activities,  and  the 
interaction  of  these  with  the  activities  of  other 
things — the  knowledge  of  which  is  Physiology. 
Beyond  this  the  living  being  has  a  position  in 
space  and  time,  which  is  its  Distribution.  All 
these  form  the  body  of  ascertainable  facts  which 
constitute  the  status  quo  of  the  hving  creature. 
But  these  facts  have  their  causes ;  and  the 
ascertainment  of  these  causes  is  the  doctrine  of 
Etiology. 

If  we  consider  what  is  knowable  about  the 
earth,  we  shall  find  that  such  earth-knowledofe — 
if  I  may  so  translate  the  word  geology — falls  into 
the  same  categories. 

What  is  termed  stratigraphical  geology  is  neither 
more  nor  less  than  the  anatomy  of  the  earth ;  and 
the  history  of  the  succession  of  the  formations  is 
the  history  of  a  succession  of  such  anatomies,  or 
corresponds  with  development,  as  distinct  from 
generation. 

The  internal  heat  of  the  earth,  the  elevation 
and  depression  of  its  crust,  its  belchings  forth 
of  vapours,  ashes,  and  lava,  are  its  activities,  in  as 
strict  a  sense  as  are  warmth  and  the  movements 
and  products  of  respiration  the  activities  of  an 
animal.  The  phenomena  of  the  seasons,  of  the 
trade  mnd's,  of  the  Gulf-stream,  are  as  much  the 


818  GEOLOGICAL  REFORM  X 

results  of  the  reaction  between  these  inner 
activities  and  outward  forces,  as  are  the  budding 
of  the  leaves  in  spring  and  their  falling  in  autumn 
the  effects  of  the  interaction  between  the  organ- 
isation of  a  plant  and  the  solar  light  and  heat. 
And,  as  the  study  of  the  activities  of  the  hving  being 
is  called  its  physiology,  so  are  these  phenomena 
the  subject-matter  of  an  analogous  telluric  physio- 
logy, to  which  we  sometimes  give  the  name  of 
meteorology,  sometimes  that  of  physical  geography, 
sometimes  that  of  geology.  Again,  the  earth  has 
a  place  in  space  and  in  time,  and  relations  to 
other  bodies  in  both  these  respects,  which  con- 
stitute its  distribution.  This  subject  is  usually 
left  to  the  astronomer;  but  a  knowledge  of  its 
broad  outlines  seems  to  me  to  be  an  essential 
constituent  of  the  stock  of  geological  ideas. 

All  that  can  be  ascertained  concerning  the 
structure,  succession  of  conditions,  actions,  and  posi- 
tion in  space  of  the  earth,  is  the  matter  of  fact  of  its 
natural  history.  But,  as  in  biology,  there  remains 
the  matter  of  reasoning  from  these  facts  to  their 
causes,  which  is  just  as  much  science  as  the  other, 
and  indeed  more ;  and  this  constitutes  geological 
aetiology. 

Having  regard  to  this  general  scheme  of  geo- 
logical knowledge  and  thought,  it  is  obvious  that 
geological  speculation  may  be,  so  to  speak,  ana- 
tomical and  developmental  speculation,  so  far  as  it 
relates  to  points  of  stratigraphical   arrangement 


X  GEOLOGICAL   REFORM  319 

which  are  out  of  reach  of  direct  observation  ;  or, 
it  may  be  physiological  speculation  so  far  as  it 
relates  to  undetermined  problems  relative  to  the 
activities  of  the  earth ;  or,  it  may  be  distributional 
speculation,  if  it  deals  with  modifications  of  the 
earth's  place  in  space  ;  or,  finally,  it  will  be  aetio- 
logical  speculation  if  it  attempts  to  deduce  the 
history  of  the  world,  as  a  whole,  from  the  known 
properties  of  the  matter  of  the  earth,  in  the  con- 
ditions in  which  the  earth  has  been  placed. 

For  the  purposes  of  the  present  discourse  I  may 
take  this  last  to  be  what  is  meant  by  "  geological 
speculation." 

Now  Uniformitarianism,  as  we  have  seen,  tends 
to  ignore  geological  speculation  in  this  sense 
altogether. 

The  one  point  the  catastrophists  and  the  uni- 
formitarians  agreed  upon,  when  this  Society  was 
founded,  was  to  ignore  it.  And  you  will  find,  if 
you  look  back  into  our  records,  that  our  revered 
fathers  in  geology  plumed  themselves  a  good  deal 
upon  the  practical  sense  and  wisdom  of  this 
proceeding.  As  a  temporary  measure,  I  do  not 
presume  to  challenge  its  wisdom ;  but  in  all 
organised  bodies  temporary  changes  are  apt  to 
produce  permanent  effects ;  and  as  time  has 
slij)ped  by,  altering  all  the  conditions  which  may 
have  made  such  mortification  of  the  scientific  flesh 
desirable,  I  think  the  effect  of  the  stream  of  cold 
water  which  has  steadily  flowed  o^er  geological 


320  GEOLOGICAL  REFORM  x 

speculation  within  these  walls  has  been  of  doubtful 
beneficence. 

The  sort  of  geological  speculation  to  which  I  am 
now  referring  (geological  aetiology,  in  short)  was 
created,  as  a  science,  by  that  famous  philosopher 
Immanuel  Kant,  when,  in  1775,  he  wrote  his 
"General  Natural  History  and  Theory  of  the 
Celestial  Bodies ;  or  an  Attempt  to  account  for 
the  Constitutional  and  the  Mechanical  Origin  of 
the  Universe  upon  Newtonian  principles."  ^ 

In  this  very  remarkable  but  seemingly  little- 
known  treatise,^  Kant  expounds  a  complete  cosmo- 
gony, in  the  shape  of  a  theory  of  the  causes  which 
have  led  to  the  development  of  the  universe 
from  diffused  atoms  of  matter  endowed  with  simple 
attractive  and  repulsive  forces. 

"  Give  me  matter,"  says  Kant, "  and  I  will  build 
the  world  ; "  and  he  proceeds  to  deduce  from  the 
simple  data  from  which  he  starts,  a  doctrine  in  all 
essential  respects  similar  to  the  well-known 
"  Nebular  Hypothesis  "  of  Laplace.^  He  accounts 
for  the  relation  of  the  masses  and  the  densities  of 
the  planets  to  their  distances  from  the  sun,  for  the 
eccentricities  of  their  orbits,  for  their  rotations,  for 


*  Grant  {History  of  Physical  Astronomy,  p.  674)  makes  but 
the  briefest  reference  to  Kant. 

-  "  Allgemeine  Naturgesehichte  und  Theorie  des  Himmels  : 
oder  Yersuch  von  der  Vevfassung  und  dem  mechanischen 
Urspvunge  des  ganzen  Weltgebaudes  nach  Newton'schen  Grund- 
satzen  abgeliandelt. " — Kant's  Sdmmtliche  JVerke,  Bd.  i.  p. 
207.  ^  Systeme  du  Mondc^  tome  ii.  chap.  6. 


X  GEOLOGICAL   REFORM  821 

their  satellites,  for  the  general  agreement  in  the 
direction  of  rotation  among  the  celestial  bodies,  for 
Saturn's  ring,  and  for  the  zodiacal  Hght.  He  finds 
in  each  system  of  worlds,  indications  that  the 
attractive  force  of  the  central  mass  will  eventually 
destroy  its  organisation,  by  concentrating  upon 
itself  the  matter  of  the  whole  system  ;  but,  as  the 
result  of  this  concentration,  he  argues  for  the 
development  of  an  amount  of  heat  which  will 
dissipate  the  mass  once  more  into  a  molecular 
chaos  such  as  that  in  which  it  began. 

Kant  pictures  to  himself  the  universe  as  once 
an  infinite  expansion  of  formless  and  diffused 
matter.  At  one  point  of  this  he  supposes  a  single 
centre  of  attraction  set  up ;  and,  by  strict  deduc- 
tions from  admitted  d}T2amical  principles,  shoAvs 
how  this  must  result  in  the  development  of  a 
prodigious  central  body,  surrounded  by  systems 
of  solar  and  planetary  worlds  in  all  stages  of 
development.  In  vivid  language  he  depicts  the 
giaat  world-maelstrom,  widening  the  margins  of  its 
prodigious  eddy  in  the  slow  progress  of  millions  of 
ages,  gradually  reclaiming  more  and  more  of  the 
molecular  waste,  and  converting  chaos  into  cosmos. 
But  what  is  gained  at  the  margin  is  lost  in  the 
centre ;  the  attractions  of  the  central  systems 
bring  their  constituents  together,  which  then,  by 
the  heat  evolved,  are  converted  once  more  into 
molecular  chaos.  Thus  the  worlds  that  are,  lie 
between  the  ruins  of  the  worlds  that  have  been, 

207 


822  GEOLOGICAL   EEFORM  x 

and  the  chaotic  materials  of  the  worlds  that  shall 
be;  and  in  spite  of  all  waste  and  destruction, 
Cosmos  is  extending  his  borders  at  the  expense  of 
Chaos. 

Kant's  further  application  of  his  views  to  the 
earth  itself  is  to  be  found  in  his  "  Treatise  on 
Physical  Geography"^  (a  term  under  which  the 
then  unkno^vn  science  of  geology  was  included),  a 
subject  which  he  had  studied  with  very  great 
care  and  on  which  he  lectured  for  many  years. 
The  fourth  section  of  the  first  part  of  this  Treatise 
is  called  "  History  of  the  great  Changes  which 
the  Earth  has  formerly  undergone  and  is  still 
undergoing,"  and  is,  in  fact,  a  brief  and  pregnant 
essay  upon  the  principles  of  geology.  Kant  gives 
an  account  first  "  of  the  gradual  changes  which 
are  now  taking  place  "  under  the  heads  of  such  as 
are  caused  by  earthquakes,  such  as  are  brought 
about  by  rain  and  rivers,  such  as  are  effected  by 
the  sea,  such  as  are  produced  by  winds  and  frost ; 
and,  finally,  such  as  result  from  the  operations  of 
man. 

The  second  part  is  devoted  to  the  "  Memorials 
of  the  Changes  which  the  Earth  has  undergone  in 
remote  Antiquity."  These  are  enumerated  as  : — 
A.  Proofs  that  the  sea  formerly  covered  the  whole 
earth.  B.  Proofs  that  the  sea  has  often  been 
changed  into  dry  land  and  then  again  into  sea. 
C.  A  discussion  of  the  various  theories  of  the 
*  Kaki's  Sdmmtli-che  Werke,  Bd.  viii.  p.  145. 


X  GEOLOGICAL   REFORM  823 

earth  put  forward  by  Scheuchzer,  Moro,  Bonnet, 
Woodward,  White,  Leibnitz,  Linnaeus,  and  Buffon. 

The  third  part  contains  an  "  Attempt  to  give  a 
sound  explanation  of  the  ancient  history  of  the 
earth." 

I  suppose  that  it  would  be  very  easy  to  pick 
holes  in  the  details  of  Kant's  speculations,  whether 
cosmological,  or  specially  telluric,  in  their  appli- 
cation. But  for  all  that,  he  seems  to  me  to  have 
been  the  first  person  to  frame  a  complete  system 
of  geological  speculation  by  founding  the  doctrine 
of  evolution. 

With  as  much  truth  as  Hutton,  Kant  could  say, 
"  I  take  things  just  as  I  find  them  at  present,  and, 
from  these,  I  reason  with  regard  to  that  which 
must  have  been."  Like  Hutton,  he  is  never  tired 
of  pointing  out  that  "  in  Nature  there  is  wisdom, 
system,  and  consistency."  And,  as  in  these  great 
principles,  so  in  believing  that  the  cosmos  has  a 
reproductive  operation  "  by  which  a  ruined  consti- 
tution may  be  repaired,"  he  forestalls  Hutton; 
while,  on  the  other  hand,  Kant  is  true  to  science. 
He  knows  no  bounds  to  geological  speculation 
but  those  of  the  intellect.  He  reasons  back  to  a 
beginning  of  the  present  state  of  things;  he 
admits  the  possibility  of  an  end. 

I  have  said  that  the  three  schools  of  geological 
speculation  which  I  have  termed  Catastrophism, 
tJniformitarianism,  and  Evolutionism,  are  com- 
monly supposed  to  be  antagonistic  to  one  another ; 


32-i  GEOLOGICAL   REFORM  x 

and  I  presume  it  will  have  become  obvious  that 
in  my  belief,  the  last  is  destined  to  swallow  up 
the  other  two.     But  it  is  proper  to  remark  that 
each  of  the  latter  has  kept  alive  the  tradition  of 
precious  truths. 

Catastrophism  has  insisted  upon  the  existence 
of  a  practically  unlimited  bank  of  force,  on  which 
the  theorist  might  draw;  and  it  has  cherished  the 
idea  of  the  development  of  the  earth  from  a  state 
in  which  its  form,  and  the  forces  which  it  exerted, 
were  very  different  from  those  we  now  know. 
That  such  difference  of  form  and  power  once 
existed  is  a  necessary  part  of  the  doctrine  of 
evolution. 

Uniformitarianism,  on  the  other  hand, has  with 
equal  justice  insisted  upon  a  practically  unlimited 
bank  of  time,  ready  to  discount  any  quantity  of 
hypothetical  paper.  It  has  kept  before  our  eyes 
the  power  of  the  infinitely  little,  time  being 
granted,  and  has  compelled  us  to  exhaust  known 
causes,  before  flying  to  the  unknown. 

To  my  mind  there  appears  to  be  no  sort  of 
necessary  theoretical  antagonism  between  Cata- 
strophism and  Uniformitarianism,  On  the  contrary, 
it  is  very  conceivable  that  catastrophes  may  be 
part  and  parcel  of  uniformity.  Let  me  illustrate 
my  case  by  analog}^  The  working  of  a  clock  is  a 
model  of  uniform  action ;  good  time-keeping 
means  uniformity  of  action.  But  the  striking 
of  the    clock   is   essentially  a   catastrophe;    the 


X  GEOLOGICAL   REFORM  325 

hammer  might  he  made  to  blow  up  a  barrel  of 
gunpowder,  or  turn  on  a  deluge  of  water ;  and,  by 
proper  arrangement,  the  clock,  instead  of  marking 
the  hours,  might  strike  at  all  sorts  of  irregular 
periods,  never  twice  alike,  in  the  intervals,  force, 
or  number  of  its  blows.  Nevertheless,  all  these 
irregular,  and  apparently  lawless,  catastrophes 
would  be  the  result  of  an  absolutely  uniformitarian 
action ;  and  we  might  have  two  schools  of  clock- 
theorists,  one  studying  the  hammer  and  the  other 
the  pendulum. 

Still  less  is  there  any  necessary  antagonism 
between  either  of  these  doctrines  and  that  of 
Evolution,  which  embraces  all  that  is  sound  in 
both  Catastrophism  and  Uniformitarianism,  while 
it  rejects  the  arbitrary  assumptions  of  the  one  and 
the,  as  arbitrary,  hmitations  of  the  other.  Nor  is 
the  value  of  the  doctrine  of  Evolution  to  the  philo- 
sophic thinker  diminished  by  the  fact  that  it  applies 
the  same  method  to  the  hving  and  the  not-living 
world ;  and  embraces,  in  one  stupendous  analogy, 
the  growth  of  a  solar  system  from  molecular  chaos, 
the  shaping  of  the  earth  from  the  nebulous  cub- 
hood  of  its  youth,  through  innumerable  changes 
and  immeasurable  ages,  to  its  present  form ;  and 
the  development  of  a  living  being  from  the  shape- 
less mass  of  protoplasm  we  term  a  germ. 

I  do  not  know  whether  Evolutionism  can  claim 
that  amount  of  currency  which  would  entitle  it 
to  be  called  British  popular  geology ;  but,  more 


326  GEOLOGICAL  REFOKM  X 

or   less  vaguely,  it   is   assuredly  present   in   the 
minds  of  most  geologists. 

Such  being  the  three  phases  of  geological 
speculation,  we  are  now  in  position  to  inquire 
which  of  these  it  is  that  Sir  William  Thomson 
calls  upon  us  to  reform  in  the  passages  which  I 
have  cited. 

It  is  obviously  Uniformitarianism  which  the 
distinguished  physicist  takes  to  be  the  representa- 
tive of  geological  speculation  in  general.  And 
thus  a  first  issue  is  raised,  inasmuch  as  many 
persons  (and  those  not  the  least  thoughtful  among 
the  younger  geologists)  do  not  accept  strict  Uni- 
formitarianism as  the  final  form  of  geological 
speculation.  We  should  say,  if  Hutton  and 
Playfair  declare  the  course  of  the  world  to  have 
been  always  the  same,  point  out  the  fallacy  by  all 
nxeans ;  but,  in  so  doing,  do  not  imagine  that 
you  are  proving  modern  geology  to  be  in  opposi- 
tion to  natural  philosophy.  I  do  not  suppose 
that,  at  the  present  day,  any  geologist  would  be 
found  to  maintain  absolute  Uniformitarianism, 
to  deny  that  the  rapidity  of  the  rotation  of  the 
earth  may  be  diminishing,  that  the  sun  Tnay  be 
waxing  dim,  or  that  the  earth  itself  may  be 
cooling.  Most  of  us,  I  suspect,  are  GalHos,  "  who 
care  for  none  of  these  things,"  being  of  opinion 
that,  true  or  fictitious,  they  have  made  no  prac- 
tical difference   to  the  earth,  during  the  period 


X  GEOLOGICAL   REFORM  827 

of  which  a  record  is  preserved  in  stratified 
deposits. 

The  accusation  that  we  have  been  running 
counter  to  the  princiiolcs  of  natural  philosophy, 
therefore,  is  devoid  of  foundation.  The  only 
question  which  can  arise  is  whether  we  have,  or 
have  not,  been  tacitly  making  assumptions  which 
are  in  opposition  to  certain  conclusions  which 
may  be  drawn  from  those  principles.  And  this 
question  subdivides  itself  into  two  : — the  first, 
are  we  really  contravening  such  conclusions  ?  the 
second,  if  we  are,  are  those  conclusions  so  firmly 
based  that  we  may  not  contravene  them  ?  I  reply 
in  the  negative  to  both  these  questions,  and  I 
will  give  you  my  reasons  for  so  doing.  Sir 
Wilham  Thomson  believes  that  he  is  able  to 
prove,  by  physical  reasonings,  "  that  the  existing 
state  of  things  on  the  earth,  life  on  the  earth — all 
geological  history  showing  continuity  of  life 
— must  be  limited  within  some  such  jDcriod 
of  time  as  one  hundred  million  years "  {Ice. 
cit.  p.  25). 

The  first  inquiry  which  arises  plainly  is,  has  it 
ever  been  denied  that  this  period  inay  be  enough 
for  the  purposes  of  geology  ? 

The  discussion  of  this  question  is  greatly 
embarrassed  by  the  vagueness  with  which  the 
assumed  limit  is,  I  will  not  say  defined,  but 
indicated, — "  some  such  period  of  past  time  as 
one  hundred  million  years."     Now  does  this  mean 


328  GEOLOGICAL   REFORM  X 

that  it  may  have  been  two,  or  three,  or  four 
hundred  million  years?  Because  this  really 
makes  all  the  difference.^ 

I  presume  that  100,000  feet  may  be  taken  as  a 
full  allowance  for  the  total  thickness  of  stratified 
rocks  containing  traces  of  life  ;  100,000  divided 
by  100,000,000  =  O'OOl.  Consequently,  the  deposit 
of  100,000  feet  of  stratified  rock  in  100,000,000 
years  means  that  the  deposit  has  taken  place 
at  the  rate  of  xgVo  ^^  ^  ^^^t,  or,  say,  qV  of  an 
inch,  per  annum. 

Well,  I  do  not  know  that  any  one  is  prepared 
to  maintain  that,  even  making  all  needful  allow- 
ances, the  stratified  rocks  may  not  have  been 
formed,  on  the  average,  at  the  rate  of  ^^  of  an 
inch  per  annum.  I  suppose  that  if  such  could  be 
shown  to  be  the  limit  of  world-gTowth,  we  could 
put  up  with  the  allowance  without  feeling  that 
our  speculations  had  undergone  any  revolution. 
And  perhaps,  after  all,  the  qualifjang  phrase 
*'  some  such  period "  may  not  necessitate  the 
assumption  of  more  than  y^^  or  g-J^  or  -g^  of 
an  inch  of  deposit  per  year,  which,  of  course, 
would  give  us  still  more  ease  and  comfort. 

But,  it  may  be  said,  that  it  is  biology,  and  not 
creolooy,  which  asks  for  so  much  time — that  the 
succession  of  life   demands   vast   intervals ;    but 

^  Sir  William  Thomson  implies  {Joe.  cit.  p,  16)  that  the  pre- 
cise time  is  of  no  consequence  :  "the  principle  is  the  same": 
hut,  as  the  principle  is  admitted,  the  whole  discussion  turns  on 
its  practical  results. 


X  GEOLOGICAL   KEFORM  329 

this  appears  to  me  to  be  reasoning  in  a  circle. 
Biology  takes  her  time  from  geology.  The  only 
reason  we  have  for  believing  in  the  slow  rate  of 
the  change  in  living  forms  is  the  fact  that  they 
jDcrsist  through  a  series  of  deposits  which,  geology 
informs  us,  have  taken  a  long  while  to  make. 
If  the  geological  clock  is  wrong,  all  the  naturalist 
will  have  to  do  is  to  modify  his  notions  of  the 
-apidity  of  change  accordingly.  And  I  venture 
to  point  out  that,  when  we  are  told  that  the 
limitation  of  the  period  during  which  living 
beings  have  inhabited  this  planet  to  one,  two,  or 
three  hundred  million  years  requires  a  complete 
revolution  in  geological  speculation,  the  onus 
prchandi  rests  on  the  maker  of  the  assertion, 
who  brings  forward  not  a  shadow  of  evidence 
in  its  support. 

Thus,  if  we  accept  the  limitation  of  time  placed 
before  us  by  Sir  W.  Thomson,  it  is  not  obvious, 
on  the  face  of  the  matter,  that  we  shall  have  to 
alter,  or  reform,  our  ways  in  any  appreciable 
degree ;  and  we  may  therefore  proceed  with  much 
calmness,  and  indeed  much  indifference,  as  to  the 
result,  to  inquire  whether  that  hmitation  is 
justified  by  the  arguments  employed  in  its 
support. 

These  argum_ents  are  three  in  number: — 
I.  The  first  is  based  upon  the  undoubted  fact 
that   the   tides   tend   to  retard  the  rate  of  the 
earth's  rotation  upon  its  axis.     That  this  must 


330  GEOLOGICAL  REFORM  X 

be  so  is  obvious,  if  one  considers,  roughly,  that 
the  tides  result  from  the  pull  which  the  sun 
and  the  moon  exert  upon  the  sea,  causing  it 
to  act  as  a  sort  of  break  upon  the  rotating  solid 
earth. 

Kant,  who  was  by  no  means  a  mere  "  abstract 
philosopher,"  but  a  good  mathematician  and  well 
versed  in  the  physical  science  of  his  time,  not 
only  proved  this  in  an  essay  of  exquisite  clear- 
ness and  intelligibility,  now  more  than  a  century 
old,  ^  but  deduced  from  it  some  of  its  more  im- 
portant consequences,  such  as  the  constant  turn- 
ing of  one  face  of  the  moon  towards  the  earth. 

But  there  is  a  long  step  from  the  demonstration 
of  a  tendency  to  the  estimation  of  the  practical 
value  of  that  tendency,  which  is  all  with  which 
we  are  at  present  concerned.  The  facts  bearing 
on  this  point  appear  to  stand  as  follows  : — 

It  is  a  matter  of  observation  that  the  moon's 
mean  motion  is  (and  has  for  the  last  3,000  years 
been)  undergoing  an  acceleration,  relatively  to 
the  rotation  of  the  earth.  Of  course  this  may 
result  from  one  of  two  causes :  the  moon  may 
really  have  been  moving  more  swiftly  in  its  orbit ; 
or  the  earth  may  have  been  rotating  more  slowly 
on  its  axis. 

^  "  Untersuchung  der  Frage  ob  die  Erde  in  ihrer  Umdrehung 
um  die  Achse,  wodurch  sie  die  Abwechselung  des  Tages  \;nd  der 
Naclit  liervorbringt,  einige  Vevanuening  seit  den  ersten  Zeiten 
ihres  Ursprunges  erlitten  habe,  kc." — Kant's  Sdmmtlicht 
IVerke,  Bd.  i.  p.  178. 


X  GEOLOGICAL  REFORM  831 

Laplace  believed  he  had  accounted  for  this  phe- 
nomenon by  the  fact  that  the  eccentricity  of  the 
earth's  orbit  has  been  diminishing  throughout 
these  3,000  years.  This  would  produce  a  diminu- 
tion of  the  mean  attraction  of  the  sun  on  the 
moon;  or,  in  other  words,  an  increase  in  the 
attraction  of  the  earth  on  the  moon;  and,  con- 
sequently, an  increase  in  the  rapidity  of  the  orbital 
motion  of  the  latter  body.  Laplace,  therefore, 
laid  the  responsibility  of  the  acceleration  upon 
the  moon,  and  if  his  views  were  correct,  the  tidal 
retardation  must  either  be  insignificant  in  amount, 
or  be  counteracted  by  some  other  agency. 

Our  great  astronomer,  Adams,  however,  appears 
to  have  found  a  flaw  in  Laplace's  calculation,  and 
to  have  shown  that  only  half  the  observed  re- 
tardation could  be  accounted  for  in  the  way  he 
had  suggested.  There  remains,  therefore,  the 
other  half  to  be  accounted  for ;  and  here,  in  the 
absence  of  all  positive  knowledge,  three  sets  of 
hypotheses  have  been  suggested. 

(a.)  M.  Delaunay  suggests  that  the  earth  is  at 
fault,  in  consequence  of  the  tidal  retardation. 
Messrs.  Adams,  Thomson,  and  Tait  work  out  this 
suggestion,  and,  "on  a  certain  assumption  as  to 
the  proportion  of  retardations  due  to  the  sun  and 
moon,"  find  the  earth  may  lose  twenty -two  seconds 
of  time  in  a  century  from  this  cause.^ 

(h.)  But  M.  Dufour  suggests  that  the  retardation 

^  Sir  W.  Thomson,  loe.  cit.  p.  14. 


832  GEOLOGICAL   REFORM  X 

of  the  earth  (which  is  hypothetically  assumed  to 
exist)  may  be  due  in  part,  or  wholly,  to  the  increase 
of  the  moment  of  inertia  of  the  earth  by  meteors 
falling  upon  its  surface.  This  suggestion  also 
meets  with  the  entire  approval  of  Sir  W.  Thomson, 
who  shows  that  meteor-dust,  accumulating  at  the 
rate  of  one  foot  in  4,000  years,  would  account  for 
the  remainder  of  retardation.^ 

(c.)  Thirdly,  Sir  W.  Thomson  brings  forward  an 
h3^othesis  of  his  own  with  respect  to  the  cause 
of  the  hypothetical  retardation  of  the  earth's 
rotation  : — 

"  Let  us  suppose  ice  to  melt  from  the  polar 
regions  (20°  round  each  pole,  we  may  say)  to  the 
extent  of  something  more  than  a  foot  thick, 
enough  to  give  1"1  foot  of  water  over  those  areas, 
or  0'006  of  a  foot  of  water  if  spread  over  the  whole 
globe,  which  would,  in  reality,  raise  the  sea-level 
by  only  some  such  undiscoverable  difference  as 
three-fourths  of  an  inch  or  an  inch.  This,  or  the 
reverse,  which  we  believe  might  happen  any  year, 
and  could  certainly  not  be  detected  without  far 
more  accurate  observations  and  calculations  for 
the  mean  sea-level  than  any  hitherto  made,  would 
slacken  or  quicken  the  earth's  rate  as  a  timekeeper 
by  one  -tenth  of  a  second  per  year."  ^ 

I  do  not  presume  to  throw  the  slightest  doubt 
upon  the  accuracy  of  any  of  the  calculations  made 
by  such  distinguished  mathematicians  as  those 
1  Sir  W.  Thomson,  loc.  cit.  p.  27.  ^  /jj^?. 


X  GEOLOGICAL   REFORM  883 

who  have  made  the  suggestions  I  have  cited.  On 
the  contrary,  it  is  necessary  to  my  argument  to 
assume  that  they  are  all  correct.  But  I  desire  to 
point  out  that  this  seems  to  be  one  of  the  many 
cases  in  which  the  admitted  accuracy  of  mathe- 
matical process  is  allowed  to  throw  a  wholly 
inadmissible  appearance  of  authority  over  the 
results  obtained  by  them.  Mathematics  may  be 
compared  to  a  mill  of  exquisite  workmanship, 
which  grinds  you  stuff  of  any  degree  of  fineness ; 
but,  nevertheless,  what  you  get  out  depends  upon 
what  you  put  in ;  and  as  the  grandest  mill  in  the 
world  will  not  extract  wheat-flour  from  peascods, 
so  pages  of  formulae  will  not  get  a  definite  result 
out  of  loose  data. 

In  the  present  instance  it  appears  to  be 
admitted : — 

1.  That  it  is  not  absolutely  certain,  after  all, 
whether  the  moon's  mean  motion  is  underofoinof 
acceleration,  or  the  earth's  rotation  retardation.^ 
And  yet  this  is  the  key  of  the  whole  position. 

2.  If  the  rapidity  of  the  earth's  rotation  is 
diminishing,  it  is  not  certain  how  much  of  that 
retardation  is  due  to  tidal  friction,  how  much  to 
meteors, — how  much  to  possible  excess  of  melting 
over  accumulation  of  polar  ice,  during  the  period 
covered  by  observation,  which  amounts,  at  the 
outside,  to  not  more  than  2,600  years. 

^  It  will  be  understood  that  I  do  not  wish  to  deny  that  the 
earth's  rotation  may  he  undergoing  retardation. 


834  GEOLOGICAL  REFORM  X 

3.  The  effect  of  a  different  distribution  of  land 
and  water  in  modifying  the  retardation  caused  by 
tidal  friction,  and  of  reducing  it,  under  some  cir- 
cumstances, to  a  minimum,  does  not  appear  to  be 
taken  into  account. 

4.  During  the  Miocene  epoch  the  polar  ice  was 
certainly  many  feet  thinner  than  it  has  been  dur- 
ing, or  since,  the  Glacial  epoch.  Sir  W.  Thomson 
tells  us  that  the  accumulation  of  something  more 
than  a  foot  of  ice  around  the  poles  (which  implies 
the  withdrawal  of,  say,  an  inch  of  water  from  the 
general  surface  of  the  sea)  will  cause  the  earth 
to  rotate  quicker  by  one-tenth  of  a  second  per 
annum.  It  would  appear,  therefore,  that  the  earth 
may  have  been  rotating,  throughout  the  whole 
period  which  has  elapsed  from  the  commencement 
of  the  Glacial  epoch  down  to  the  present  time,  one, 
or  more,  seconds  per  annum  quicker  than  it 
rotated  during  the  Miocene  epoch. 

But,  according  to  Sir  W.  Thomson's  calculation, 
tidal  retardation  will  only  account  for  a  retardation 
of  22"  in  a  century,  or  y%%-  (say  i)  of  a  second  per 
annum. 

Thus,  assuming  that  the  accumulation  of  polar 
ice  since  the  Miocene  epoch  has  only  been  suffi- 
cient to  produce  ten  times  the  effect  of  a  coat  of 
ice  one  foot  thick,  we  shall  have  an  accelerating 
cause  which  covers  all  the  loss  from  tidal  action, 
and  leaves  a  balance  of  4  of  a  second  per  annum 
in  the  way  of  acceleration. 


X  GEOLOGICAL   REFORM  335 

If  tidal  retardation  can  be  thus  checked  and 
overthrown  by  other  temporary  conditions,  what 
becomes  of  the  confident  assertion,  based  upon  the 
assumed  uniformity  of  tidal  retardation,  that  ten 
thousand  million  years  ago  the  earth  must  have 
been  rotating  more  than  twice  as  fast  as  at 
present,  and,  therefore,  that  we  geologists  are 
"  in  direct  opposition  to  the  principles  of  Natural 
Philosophy "  if  we  spread  geological  history  over 
that  time  ? 

II.  The  second  argument  is  thus  stated  by  Sir 
W.  Thomson  : — "  An  article,  by  myself,  published 
in  '  Macmillan's  Magazine  '  for  March  1862,  on  the 
age  of  the  sun's  heat,  explains  results  of  investiga- 
tion into  various  questions  as  to  possibilities 
regarding  the  amount  of  heat  that  the  sun  could 
have,  dealing  with  it  as  you  would  with  a  stone,  or  a 
piece  of  matter,  only  taking  into  account  the  sun's 
dimensions,  which  showed  it  to  be  possible  that 
the  sun  may  have  already  illuminated  the  earth 
for  as  many  as  one  hundred  million  years,  but  at 
the  same  time  rendered  it  almost  certain  that  he 
had  not  illuminated  the  earth  for  five  hundred 
millions  of  years.  The  estimates  here  are  neces- 
sarily very  vague  ;  but  yet,  vague  as  they  are,  I  do 
not  know  that  it  is  possible,  upon  any  reasonable 
estimate  founded  on  known  properties  of  matter, 
to  say  that  we  can  believe  the  sun  has  really  ilium  • 
inated  the  earth  for  five  hundred  million  years."  ^ 
*  I/^.  ciL  p.  20. 


336  GEOLOGICAL   REFORM  X 

I  do  not  wish  to  "  Hansardise "  Sir  William 
Thomson  by  laying  much  stress  on  the  fact  that, 
only  fifteen  years  ago  he  entertained  a  totally  differ- 
ent view  of  the  origin  of  the  sun's  heat,  and 
believed  that  the  energy  radiated  from  year  to 
year  was  supphed  from  year  to  year — a  doctrine 
which  would  have  suited  Hutton  perfectly.  But 
the  fact  that  so  eminent  a  physical  philosopher 
has,  thus  recently,  held  views  opposite  to  those 
which  he  now  entertains,  and  that  he  confesses  his 
own  estimates  to  be  "  very  vague,"  justly  entitles 
us  to  disregard  those  estimates,  if  any  distinct 
facts  on  our  side  go  against  them.  However,  I  am 
not  aware  that  such  facts  exist.  As  I  have  already 
said,  for  anything  I  know,  one,  two,  or  three  hun- 
dred millions  of  years  may  serve  the  needs  of 
geologists  perfectly  well. 

III.  The  third  line  of  argument  is  based  upon 
the  temperature  of  the  interior  of  the  earth.  Sir 
W.  Thomson  refers  to  certain  investigations  which 
prove  that  the  present  thermal  condition  of  the 
interior  of  the  earth  implies  either  a  heating  of 
the  earth  within  the  last  20,000  years  of  as  much 
as  100'  F.,  or  a  greater  heating  all  over  the  surface 
at  some  time  further  back  than  20,000  years,  and 
then  proceeds  thus  : — 

"  Now,  are  geologists  prepared  to  admit  that,  at 
some  time  within  the  last  20,000  years,  there  has 
been  all  over  the  earth  so  high  a  temperature  as 
that  ?     I  presume  not ;  no  geologist — no  w.odern 


X  GEOLOGICAL   REFORM  837 

geologist — would  for  a  moment  admit  tlie  hypo- 
thesis that  the  present  state  of  underground  heat 
is  due  to  a  heating  of  the  surface  at  so  late  a 
period  as  20,000  years  ago.  If  that  is  not  admitted 
we  are  driven  to  a  greater  heat  at  some  time  more 
than  20,000  years  ago.  A  greater  heating  all 
over  the  surface  than  100°  Fahrenheit  would  kill 
nearly  all  existing  plants  and  animals,  I  may 
safely  say.  Are  modern  geologists  prepared  to 
say  that  all  life  was  killed  off  the  earth  50,000, 
100,000,  or  200,000  years  ago  ?  For  the  uniformity 
theory,  the  further  back  the  time  of  high  surface- 
temperature  is  put  the  better ;  but  the  further 
back  the  time  of  heating,  the  hotter  it  must  have 
been.  The  best  for  those  who  draw  most  largely 
on  time  is  that  which  puts  it  furthest  back ;  and 
that  is  the  theory  that  the  heating  was  enough  to 
melt  the  whole.  But  even  if  it  was  enough  to 
melt  the  whole,  we  must  still  admit  some  limit, 
such  as  fifty  million  years,  one  hundred  million 
years,  or  two  or  three  hundred  million  years  ago. 
Beyond  that  we  cannot  go."  ^ 

It  will  be  observed  that  the  "  limit "  is  once 
again  of  the  vaguest,  ranging  from  50,000,000 
years  to  300,000,000.  And  the  reply  is,  once 
more,  that,  for  anjrfching  that  can  be  proved  to  the 
contrary,  one  or  two  hundred  million  years  might 
serve  the  purpose,  even  of  a  thoroughgoing  Hut- 
tonian  uniformitarian,  very  well. 
^  Loc.  cit.  p.  24. 
208 


338  GEOLOGICAL   REFORM  X 

But  if,  on  the  other  hand,  the  100,000,000  or 
200,000,000  years  appear  to  be  insufficient  for 
geological  purposes,  we  must  closely  criticise  the 
method  by  which  the  limit  is  reached.  The 
argument  is  simple  enough.  Assuming  the  earth 
to  be  nothing  but  a  cooling  mass,  the  quantity  of 
heat  lost  per  year,  siippcsi7ig  the  rate  of  cooling  to 
have  been  uniform,  multipHed  by  any  given 
number  of  years,  will  be  given  the  minimum 
temperature  that  number  of  years  ago. 

But  is  the  earth  nothing  but  a  cooling  mass, 
"like  a  hot-water  jar  such  as  is  used  in  carriages," 
or  "  a  globe  of  sandstone,"  and  has  its  cooling 
been  uniform  ?  An  affirmative  answer  to  both 
these  questions  seems  to  be  necessary  to  the 
validity  of  the  calculations  on  which  Sir  W. 
Thomson  lays  so  much  stress. 

Nevertheless  it  surely  may  be  urged  that  such 
affirmative  answers  are  purely  hypothetical,  and 
that  other  suppositions  have  an  equal  right  to 
consideration. 

For  example,  is  it  not  possible  that,  at  the 
prodigious  temperature  which  would  seem  to 
exist  at  100  miles  below  the  surface,  aU  the 
metallic  bases  may  behave  as  mercury  does  at  a 
red  heat,  when  it  refuses  to  combine  with  oxygen  ; 
while,  nearer  the  surface,  and  therefore  at  a  lower 
temperature,  they  may  enter  into  combination  (as 
mercury  does  with  oxygen  a  few  degrees  below  its 
boiling-point),  and  so  give  rise  to  a  heat  totally 


X  GEOLOGICAL   REFORM  889 

distinct  from  that  which  they  possess  as  cooHng 
bodies  ?  And  has  it  not  also  been  proved  by 
recent  researches  that  the  quahty  of  the  atmo- 
sphere may  immensely  affect  its  permeability  to 
heat ;  and,  consequently,  profoundly  modify  the 
rate  of  cooling  the  globe  as  a  whole  ? 

I  do  not  think  it  can  be  denied  that  such  con- 
ditions may  exist,  and  may  so  greatly  affect  the 
supply,  and  the  loss,  of  terrestrial  heat  as  to 
destroy  the  value  of  any  calculations  which  leave 
them  out  of  sight. 

My  functions  as  your  advocate  are  at  an  end.  I 
speak  with  more  than  the  sincerity  of  a  mere 
advocate  when  I  express  the  belief  that  the  case 
against  us  has  entirely  broken  down.  The  cry  for 
reform  which  has  been  raised  without,  is  super- 
fluous, inasmuch  as  w"e  have  long  been  reforming 
from  within,  with  all  needful  speed.  And  the 
critical  examination  of  the  grounds  upon  which 
the  very  grave  charge  of  opposition  to  the  principles 
of  Natural  Philosophy  has  been  brought  against 
us,  rather  shows  that  we  have  exercised  a  wise 
discrimination  in  declining,  for  the  present,  to 
meddle  with  our  foundations. 


XI 


PALEONTOLOGY   AND    THE    DOCTRINE 
OF   EVOLUTION 

[1870] 

It  is  now  eight  years  since,  in  the  absence  of 
the  late  Mr.  Leonard  Horner,  who  then  presided 
over  us,  it  fell  to  my  lot,  as  one  of  the  Secretaries 
of  this  Society,  to  draw  up  the  customary  Annual 
Address.  I  availed  myself  of  the  opportunity  to 
endeavour  to  "  take  stock  "  of  that  yjortion  of  the 
science  of  biology,  which  is  commonly  called 
"  palaeontology,"  as  it  then  existed ;  and,  dis- 
cussing one  after  another  the  doctrines  held  by 
palseontologists,  I  put  before  you  the  results  of 
my  attempts  to  sift  the  well-established  from 
the  h3^pothetical  or  the  doubtful.  Permit  me 
briefly  to  recall  to  your  minds  what  those  results 
were : — 

1.  The  Hving  population  of   all   parts  of   the 
earth's   surface   which   have   yet  been  examined 


XI  PALEONTOLOGY   AND   EVOLUTION  341 

has  undergone  a  succession  of  changes  which, 
upon  the  whole,  have  been  of  a  slow  and  gradual 
character. 

2.  When  the  fossil  remains  which  are  the 
evidences  of  these  successive  changes,  as  they 
have  occurred  in  any  two  more  or  less  distant 
parts  of  the  surface  of  the  earth,  are  com- 
pared, they  exhibit  a  certain  broad  and  general 
parallelism.  In  other  words,  certain  forms  of 
life  in  one  locality  occur  in  the  same  general 
order  of  succession  as,  or  are  homotaxicd  with, 
similar  forms  in  the  other  locahty. 

3.  Homotaxis  is  not  to  be  held  identical  with 
synchronism  wdthout  independent  evidence.  It 
is  possible  that  similar,  or  even  identical,  faunse 
and  flor«  in  two  different  locahties  may  be  of 
extremely  diiBferent  ages,  if  the  term  "  age "  is 
used  in  its  proper  chronological  sense.  I  stated 
that  "  geographical  provinces,  or  zones,  may  have 
been  as  distinctly  marked  in  the  Palaeozoic  epoch 
as  at  present ;  and  those  seemingly  sudden  ap- 
pearances of  new  genera  and  species  which  we 
ascribe  to  new  creation,  may  be  simple  results 
of  migration." 

4.  The  opinion  that  the  oldest  known  fossils 
are  the  earhest  forms  of  hfe  has  no  sohd  founda- 
tion. 

5.  If  we  confine  ourselves  to  positively  ascer- 
tained facts,  the  total  amount  of  change  in  the 
forms  of  animal    and    vegetable    life,  since    the 


842  PALAEONTOLOGY   AND   EVOLUTION  xi 

existence  of  such  forms  is  recorded,  is  small. 
When  compared  with  the  lapse  of  time  since 
the  first  appearance  of  these  forms,  the  amount 
of  change  is  wonderfully  small.  Moreover,  in 
each  great  group  of  the  animal  and  vegetable 
kingdoms,  there  are  certain  forms  which  I  termed 
Persistent  Types,  which  have  remained,  with 
but  very  little  apparent  change,  from  their  first 
appearance  to  the  present  time. 

6.  In  answer  to  the  question  "  What,  then,  does 
an  impartial  survey  of  the  positively  ascertained 
truths  of  palaeontology  testify  in  relation  to  the 
common  doctrines  of  progressive  modification, 
which  suppose  that  modification  to  have 
taken  place  by  a  necessary  progress  from  more 
to  less  embryonic  forms,  from  more  to  less  general- 
ised types,  within  the  limits  of  the  period 
represented  by  the  fossiliferous  rocks  ? "  I  reply, 
"  It  negatives  these  doctrines ;  for  it  either 
show  us  no  evidence  of  such  modification,  or 
demonstrates  such  modification  as  has  occurred 
to  have  been  very  slight ;  and,  as  to  the  nature 
of  that  modification,  it  yields  no  evidence  what- 
soever that  the  earlier  members  of  any  long-con- 
tinued group  were  more  generalised  in  structure 
than  the  later  ones." 

I  think  that  I  cannot  employ  my  last  opportu- 
nity of  addressing  you,  officially,  more  properly — > 
I  may  say  more  dutifully — than  in  revising  these 
old  judgments  with  such  help  as  further  know- 


XI  PALEONTOLOGY   AND  EVOLUTION  343 

ledge  and  reflection,  and  an  extreme  desire  to  get 
at  the  truth,  may  afford  me. 

1.  With  respect  to  the  first  proposition,  I  may- 
remark  that  whatever  may  be  the  case  among  the 
physical  geologists,  catastrophic  palaeontologists 
are  practically  extinct.  It  is  now  no  part  of 
recognised  geological  doctrine  that  the  species  of 
one  formation  all  died  out  and  were  replaced  by  a 
brand-new  set  in  the  next  formation.  On  the 
contrary,  it  is  generally,  if  not  universally,  agreed 
that  the  succession  of  life  has  been  the  result  of  a 
slow  and  gradual  replacement  of  species  by  species ; 
and  that  all  appearances  of  abruptness  of  change 
are  due  to  breaks  in  the  series  of  deposits,  or  other 
changes  in  physical  conditions.  The  continuity  of 
living  forms  has  been  unbroken  from  the  earliest 
times  to  the  present  day. 

2,  3.  The  use  of  the  word  "  homotaxis  "  instead 
of  "  synchronism  "  has  not,  so  far  as  I  know,  found 
much  favour  in  the  eyes  of  geologists.  I  hope, 
therefore,  that  it  is  a  love  for  scientific  caution, 
and  not  mere  personal  affection  for  a  bantling  of 
my  own,  which  leads  me  still  to  think  that  the 
change  of  phrase  is  of  importance,  and  that 
the  sooner  it  is  made,  the  sooner  shall  we  get  rid 
of  a  number  of  pitfalls  which  beset  the  reasoner 
upon  the  facts  and  theories  of  geology. 

One  of  the  latest  pieces  of  foreign  intelligence 
which  has  reached  us  is  the  information  that  the 
Austrian   geologists   have,  at  last,  succumbed   to 


844  PALEONTOLOGY  AND   EVOLUTION  xi 

fche  weighty  evidence  which  M.  Barrande  has 
accumulated,  and  have  admitted  the  doctrine  of 
colonies.  But  the  admission  of  the  doctrine  of 
colonies  implies  the  further  admission  that  even 
identity  of  organic  remains  is  no  proof  of  the 
synchronism  of  the  deposits  which  contain 
them. 

4.  The  discussions  touching  the  Eozoon,  which 
commenced  in  1864,  have  abundantly  justified  the 
fourth  proposition.  In  1862,  the  oldest  record  of 
life  was  in  the  Cambrian  rocks ;  but  if  the  Eozoon 
be,  as  Principal  Dawson  and  Dr.  Carpenter  have 
shown  so  much  reason  for  believing,  the  remains 
of  a  living  being,  the  discovery  of  its  true  nature 
carried  life  back  to  a  period  which,  as  Sir  William 
Logan  has  observed,  is  as  remote  from  that  during 
which  the  Cambrian  rocks  were  deposited,  as  the 
Cambrian  epoch  itself  is  from  the  tertiaries.  In 
other  words,  the  ascertained  duration  of  life  upon 
the  globe  was  nearly  doubled  at  a  stroke. 

5.  The  significance  of  persistent  types,  and  of 
the  small  amount  of  change  which  has  taken  place 
even  in  those  forms  which  can  be  shown  to  have 
been  modified,  becomes  greater  and  greater  in  my 
eyes,  the  longer  I  occupy  myself  with  the  biology 
of  the  past. 

Consider  how  long  a  time  has  elapsed  since  the 
Miocene  epoch.  Yet,  at  that  time  there  is  reason 
to  believe  that  every  important  group  in  every 
order  of  the  Mammalia  was  represented.     Even  the 


XI  PALEONTOLOGY   AND   EVOLUTION  845 

comparatively  scanty  Eocene  fauna  3delds  examples 
of  the  orders  Cheiroptera,  Insectwora,  Rodentia,  and 
Pcrissodactyla ;  of  Articdactyla  under  both  the 
Ruminant  and  the  Porcine  modifications ;  of  Carni- 
vora,  Cetacea,  and  Marsupialia. 

Or,  if  we  go  back  to  the  older  half  of  the  Meso- 
zoic  epoch,  how  truly  surprising  it  is  to  find 
every  order  of  the  Re][)tilia,  except  the  Ophidia, 
represented ;  while  some  groups,  such  as  the 
Omithoscelida  and  the  Pterosauria,  more  specialised 
than  any  which  now  exist,  abounded. 

There  is  one  division  of  the  Amphibia  which 
offers  especially  important  evidence  upon  this 
point,  inasmuch  as  it  bridges  over  the  gap  between 
the  Mesozoic  and  the  Palaeozoic  formations  (often 
supposed  to  be  of  such  prodigious  magnitude),  ex- 
tending, as  it  does,  from  the  bottom  of  the  Car- 
boniferous series  to  the  top  of  the  Trias,  if  not 
into  the  Lias.  I  refer  to  the  LabjTinthodonts. 
As  the  Address  of  1862  was  passing  through  the 
press,  I  was  able  to  mention,  in  a  note,  the 
discovery  of  a  large  Labyrinthodont,  with  well- 
ossified  vertebrse,  in  the  Edinburgh  coal-field. 
Since  that  time  eight  or  ten  distinct  genera  of 
Labyrinthodonts  have  been  discovered  in  the 
Carboniferous  rocks  of  England,  Scotland,  and 
Ireland,  not  to  mention  the  American  forms 
described  by  Principal  Dawson  and  Professor 
Cope.  So  that,  at  the  present  time,  the  Labpin- 
thodont  Fauna  of  the  Carboniferous  rocks  is  moie 


846  PALEONTOLOGY   AND  EVOLUTION  xi 

extensive  and  diversified  than  that  of  the  Trias, 
while  its  chief  types,  so  far  as  osteology  enables 
us  to  judge,  are  quite  as  highly  organised.  Thus 
it  is  certain  that  a  comparatively  highly  organised 
vertebrate  type,  such  as  that  of  the  Labyiintho- 
donts,  is  capable  of  persisting,  with  no  considerable 
change,  through  the  period  represented  by  the 
vast  deposits  which  constitute  the  Carboniferous, 
the  Permian,  and  the  Triassic  formations. 

The  very  remarkable  results  which  have  been 
brought  to  light  by  the  sounding  and  dredging 
operations,  which  have  been  carried  on  with  such 
remarkable  success  by  the  expeditions  sent  out  by 
our  own,  the  American,  and  the  Swedish  Govern- 
ments, under  the  supervision  of  able  naturalists, 
have  a  bearing  in  the  same  direction.  These  in- 
vestigations have  demonstrated  the  existence,  at 
great  depths  in  the  ocean,  of  living  animals  in 
some  cases  identical  with,  in  others  very  similar 
to,  those  which  are  found  fossilised  in  the  white 
chalk.  The  G-loligcrince,  Cyatholiths,  Cocco- 
spheres,  Discoliths  in  the  one  are  absolutely 
identical  with  those  in  the  other  ;  there  are 
identical,  or  closely  analogous,  species  of  Sponges, 
Echinoderms,  and  Brachiopods.  Off  the  coast  of 
Portugal,  there  now  lives  a  species  of  Bcryx,  which, 
doubtless,  leaves  its  bones  and  scales  here  and 
there  in  the  Atlantic  ooze,  as  its  predecessor  left 
its  spoils  in  the  mud  of  the  sea  of  the  Cretaceous 
epoch. 


XI  PALJEONTOLOGY"  AND   EVOLUTION  847 

Many  years  ago^  I  ventured  to  speak  of  the 
Atlantic  mud  as  "  modern  chalk,"  and  I  know  of 
no  fact  inconsistent  with  the  view  which  Professor 
Wyville  Thomson  has  advocated,  that  the  modem 
chalk  is  not  only  the  Kneal  descendant  of  the 
ancient  chalk,  but  that  it  remains,  so  to  speak,  in 
the  possession  of  the  ancestral  estate;  and  that 
from  the  Cretaceous  period  (if  not  much  earlier) 
to  the  present  day,  the  deep  sea  has  covered  a 
large  part  of  what  is  now  the  area  of  the  Atlantic. 
But  if  Glchigerina,  and  Terebratula  caput-serpentis 
and  Beryx,  not  to  mention  other  forms  of  animals 
and  of  plants,  thus  bridge  over  the  interval 
between  the  present  and  the  Mesozoic  periods,  is 
it  possible  that  the  majority  of  other  living  things 
underwent  a  "  sea-change  into  something  new  and 
strange  "  all  at  once  ? 

6.  Thus  far  I  have  endeavoured  to  expand  and 
to  enforce  by  fresh  arguments,  but  not  to  modify 
in  any  important  respect,  the  ideas  submitted  to 
you  on  a  former  occasion.  But  when  I  come  to 
the  propositions  touching  progressive  modifica- 
tion, it  appears  to  me,  with  the  help  of  the  new 
light  which  has  broken  from  various  quarters,  that 
there  is  much  ground  for  softening  the  somewhat 
Brutus-like  severity  with  which,  in  1862,  I  dealt 
with  a  doctrine,  for  the  truth  of  which  I  should 
have  been  glad  enough  to  be  able  to  find  a  good 

^  See  an  article  in  the  Saturday  Eevicia,  for  1858,  on  "  Chalk, 
Ancient  and  Modem." 


348  PALAEONTOLOGY   AND   EVOLUTION  xi 

foundation.  So  far,  indeed,  as  the  Invertehrata  and 
the  lower  Vertehrata  are  concerned,  the  facts  and 
the  conclusions  which  are  to  be  drawn  from  them 
appear  to  me  to  remain  what  they  were.  For 
anything  that,  as  yet,  appears  to  the  contrary,  the 
earhest  known  Marsupials  may  have  been  as 
highly  organised  as  their  living  congeners  ;  the 
Permian  Hzards  show  no  signs  of  inferiority  to 
those  of  the  present  day;  the  Labyrinthodonts 
cannot  be  placed  below  the  living  Salamander  and 
Triton ;  the  Devonian  Ganoids  are  closely  related 
to  Poly'pteTiiS  and  to  Lejndosiren. 

But  when  we  turn  to  the  higher  Verfxhratay 
the  results  of  recent  investigations,  however  we 
may  sift  and  criticise  them,  seem  to  me  to  leave  a 
clear  balance  in  favour  of  the  doctrine  of  the 
evolution  of  Hving  forms  one  from  another. 
Nevertheless,  in  discussing  this  question,  it  is 
very  necessary  to  discriminate  carefully  between 
the  different  kinds  of  evidence  from  fossil  re- 
mains which  are  brought  forward  in  favour  of 
evolution. 

Every  fossil  which  takes  an  intermediate  place 
between  forms  of  life  already  known,  may  be  said, 
so  far  as  it  is  intermediate,  to  be  evidence  in 
favour  of  evolution,  inasmuch  as  it  shows  a  possible 
road  by  which  evolution  may  have  taken  place. 
But  the  mere  discovery  of  such  a  form  does  not, 
in  itself,  prove  that  evolution  took  place  by  and 
through  it,  nor  does  it  constitute  more  than  pre- 


XI 


PALEONTOLOGY   AND   EVOLUTION  349 


sumptive  evidence  in  favour  of  evolution  in 
general.  Suppose  A,  B,  C  to  be  three  forms, 
while  B  is  intermediate  in  structure  between  A 
and  C.  Then  the  doctrine  of  evolution  offers  four 
possible  alternatives.  A  may  have  become  C  by 
way  of  B ;  or  C  may  have  become  A  by  way  of  B  ; 
or  A  and  C  may  be  independent  modifications  of 
B ;  or  A,  B,  and  C  may  be  independent  modifica- 
tions of  some  unknown  D.  Take  the  case  of  the 
Pigs,  the  Ancplotheridcc,  and  the  Ruminants. 
The  AnoplotJieridce  are  intermediate  between  the 
first  and  the  last ;  but  this  does  not  tell  us  whether 
the  Ruminants  have  come  from  the  Pigs,  or  the 
Pigs  from  Ruminants^  or  both  from  Anajylotheridce, 
or  whether  Pigs,  Ruminants,  and  Anoplotheridce 
alike  may  not  have  diverged  from  some  common 
stock. 

But  if  it  can  be  shown  that  A,  B,  and  C  exhibit 
successive  stages  in  the  degree  of  modification,  or 
specialisation,  of  the  same  tjipe ;  and  if,  farther,  it 
can  be  proved  that  they  occur  m  successively 
newer  deposits,  A  being  in  the  oldest  and  C  in 
the  newest,  then  the  intermediate  character  of  B 
has  quite  another  importance,  and  I  should  accept 
it,  without  hesitation,  as  a  link  in  the  genealogy 
of  C.  I  should  consider  the  burden  of  proof  to  be 
thrown  upon  any  one  who  denied  C  to  have  been 
derived  from  A  by  way  of  B,  or  in  some  closely 
analogous  fashion ;  for  it  is  always  probable  that 
one  may  not  hit  upon  the  exact  line  of  filiation, 


350  PALEONTOLOGY   AND   EVOLUTION  xi 

and,  in  dealing  with  fossils,  may  mistake  uncles 
and  nephews  for  fathers  and  sons. 

I  think  it  necessary  to  distinguish  between  the 
former  and  the  latter  classes  of  intermediate  forms, 
as  intercalary  types  and  linear  types.  When  I 
apply  the  former  term,  I  merely  mean  to  say  that 
as  a  matter  of  fact,  the  form  B,  so  named,  is  inter- 
mediate between  the  others,  in  the  sense  in  which 
the  Anoplotherium  is  intermediate  between  the 
Pigs  and  the  Ruminants — without  either  affirming, 
or  denying,  any  direct  genetic  relation  between 
the  three  forms  involved.  When  I  apply  the 
latter  term,  on  the  other  hand,  I  mean  to  express 
the  opinion  that  the  forms  A,  B,  and  C  constitute 
a  line  of  descent,  and  that  B  is  thus  part  of  the 
lineage  of  C 

From  the  time  when  Cuvier's  wonderful  re- 
searches upon  the  extinct  Mammals  of  the  Paris 
gypsum  first  made  intercalary  types  known,  and 
caused  them  to  be  recognised  as  such,  the  number 
of  such  forms  has  steadily  increased  among  the 
higher  Mammalia.  Not  only  do  we  now  know 
numerous  intercalary  forms  of  Ungulata,  but  M. 
Gaudry's  great  monograph  upon  the  fossils  of 
Pikermi  (which  strikes  me  as  one  of  the  most 
perfect  pieces  of  palseontological  work  I  have  seen 
for  a  long  time)  shows  us,  among  the  Primates, 
Mesopithecus  as  an  intercalary  form  between  the 
Semnopitheci  and  the  Macaci ;  and  among  the 
Carnivora,  Hycenictis  and  Iditherium  as  intercalary, 


XI  PALEONTOLOGY   AND  EVOLUTION  351 

or,  perhaps,  linear  types  between  the  Viverridne 
and  the  Hycenidce. 

Hardly  any  order  of  the  higher  Mammalia 
stands  so  apparently  separate  and  isolated  from 
the  rest  as  that  of  the  Cdacea ;  though  a  careful 
consideration  of  the  structure  of  the  pinnipede 
Carnivora,  or  Seals,  shows,  in  them,  many  an 
approximation  towards  the  still  more  completely 
marine  mammals.  The  extinct  Zeuglcclon,  how- 
ever, presents  us  with  an  intercalary  form  between 
the  t}q)e  of  the  Seals  and  that  of  the  Whales. 
The  skull  of  this  great  Eocene  sea-monster,  in 
fact,  shows  by  the  narrow  and  prolonged  inter- 
orbital  region ;  the  extensive  union  of  the  parietal 
bones  in  a  sagittal  suture ;  the  well-developed 
nasal  bones ;  the  distinct  and  large  incisors 
implanted  in  premaxillary  bones,  which  take  a 
full  share  in  bounding  the  fore  part  of  the  gape  ; 
the  two-fano-ed  molar  teeth  with  triangular  and 
serrated  crowns,  not  exceeding  five  on  each  side 
in  each  jaw ;  and  the  existence  of  a  deciduous 
dentition — its  close  relation  with  the  Seals. 
While,  on  the  other  hand,  the  produced  rostral 
form  of  the  snout,  the  long  symphysis,  and  the 
low  coronary  process  of  the  mandible  are  approxi- 
mations to  the  cetacean  form  of  those  parts. 

The  scapula  resembles  that  of  the  cetacean 
Hyperoodon,  but  the  supra-spinous  fossa  is  larger 
and  more  seal-like ;  as  is  the  humerus,  which 
differs  from  that  of  the  Cdacea  in  presenting  true 


352  PALAEONTOLOGY  AND   EVOLUTION  xi 

articular  surfaces  for  the  free  jointing  of  the 
bones  of  the  fore-arm.  In  the  apparently  com- 
plete absence  of  hinder  limbs,  and  in  the  characters 
of  the  vertebral  column,  the  Zeuglodon  lies  on  the 
cetacean  side  of  the  boundary  line  ;  so  that  upon 
the  whole,  the  Zeuglodonts,  transitional  as  they 
are,  are  conveniently  retained  in  the  cetacean 
order.  And  the  publication,  in  1864,  of  M.  Van 
Beneden's  memoir  on  the  Miocene  and  Pliocene 
Squalcdon,  furnished  much  better  means  than 
anatomists  previously  possessed  of  fitting  in 
another  link  of  the  chain  which  connects  the 
existing  Cctacca  with  Zcuglcdon.  The  teeth  are 
much  more  numerous,  although  the  molars  exhibit 
the  zeuglodont  double  fang ;  the  nasal  bones  are 
very  short,  and  the  upper  surface  of  the  rostrum 
presents  the  groove,  filled  up  during  life  by  the 
prolongation  of  the  ethmoidal  cartilage,  which  is 
so  characteristic  of  the  majority  of  the  Cetacea. 

It  appears  to  me  that,  just  as  among  the 
existing  Carnivora,  the  walruses  and  the  eared 
seals  are  intercalary  forms  between  the  fissipede 
Carnivora  and  the  ordinary  seals,  so  the  Zeuglo- 
donts are  intercalary  between  the  Carnivora,  as  a 
whole,  and  the  Cetacea.  Whether  the  Zeuglodonts 
are  also  linear  types  in  their  relation  to  these  two 
groups  cannot  be  ascertained,  until  we  have  more 
definite  knowledge  than  we  possess  at  present, 
respecting  the  relations  in  time  of  the  Carnivora 
and  Cetacea. 


XI  PAL^OXTOLOGY   AND   EVOLUTION  358 

Thus  far  we  have  been  concerned  with  the 
intercalary  types  which  occupy  the  intervals 
between  Families  or  Orders  of  the  same  class  ; 
but  the  investigations  which  have  been  carried 
on  by  Professor  Gegenbaur,  Professor  Cope,  and 
myself  into  the  structure  and  relations  of  the 
extinct  reptiUan  forms  of  the  Ornithoscelida  (or 
Dinosauricb  and  CGmpsognatha)  have  brought  to 
light  the  existence  of  intercalary  forms  betv/een 
what  have  hitherto  been  always  regarded  as  very 
distinct  classes  of  the  vertebrate  sub-kino^dom, 
namely  Beptilia  and  Aves.  Whatever  inferences 
may,  or  may  not,  be  drawn  from  the  fact,  it  is 
now  an  estabhshed  truth  that,  in  many  of  these 
Ornithoscelida,  the  hind  limbs  and  the  pelvis  are 
much  more  similar  to  those  of  Birds  than  they 
are  to  those  of  Reptiles,  and  that  these  Bird- 
reptiles,  or  Reptile-birds,  were  more  or  less  com- 
pletely bipedal. 

When  I  addressed  you  in  1862,  I  should  have 
been  bold  indeed  had  I  suggested  that  palaeon- 
tology would  before  long  show  us  the  possibility 
of  a  direct  transition  from  the  type  of  the  lizard 
to  that  of  the  ostrich.  At  the  present  moment, 
we  have,  in  the  Ornithoscelida,  the  intercalary  t}^e, 
which  proves  that  transition  to  be  something 
more  than  a  possibility;  but  it  is  very  doubtful 
whether  any  of  the  genera  of  Ornithoscelida  with 
which  we  are  at  present  acquainted  are  the  actua] 
linear   types   by  which   the  transition  from  the 

209 


854  PALEONTOLOGY   AND   EVOLUTION  xi 

lizard  to  the  bird  was  effected.  These,  very  prob- 
ably, are  still  hidden  from  us  in  the  older  for- 
mations. 

Let  us  now  endeavour  to  find  some  cases  of 
true  linear  types,  or  forms  which  are  intermediate 
between  others  because  they  stand  in  a  direct 
genetic  relation  to  them.  It  is  no  easy  matter  to 
find  clear  and  unmistakable  evidence  of  filiation 
among  fossil  animals;  for,  in  order  that  such 
evidence  should  be  quite  satisfactory,  it  is  necessary 
that  we  should  be  acquainted  with  all  the  most 
important  features  of  the  organisation  of  the 
animals  which  are  supposed  to  be  thus  related,  and 
not  merely  with  the  fragments  upon  which  the 
genera  and  species  of  the  palaeontologist  are  so 
often  based.  M.  Gaudry  has  arranged  the  species 
of  HycenidcB,  Prohoscidea,  Bhinccerotidce,  and  Equidce 
in  their  order  of  filiation  from  their  earliest  appear- 
ance in  the  Miocene  epoch  to  the  present  time,  and 
Professor  Riitimeyer  has  drawn  up  similar  schemes 
for  the  Oxen  and  other  Ungulata — with  what,  I 
am  disposed  to  think,  is  a  fair  and  probable  approxi- 
mation to  the  order  of  nature.  But,  as  no  one  is 
better  aware  than  these  two  learned,  acute,  and 
philosophical  biologists,  all  such  arrangements 
must  be  regarded  as  provisional,  except  in  those 
cases  in  which,  by  a  fortunate  accident,  large 
series  of  remains  are  obtainable  from  a  thick  and 
widespread  series  of  deposits.  It  is  easy  to 
accumulate  probabilities — hard  to  make  out  somB 


XI  PALEONTOLOGY   AND   EVOLUTION  855 

particular  case  in  such  a  way  that  it  will  stand 
rigorous  criticism. 

After  much  search,  however,  I  think  that  such 
a  case  is  to  be  made  out  in  favour  of  the  pedigree 
of  the  Horses. 

The  genus  Equus  is  represented  as  far  back  as 
the  latter  part  of  the  Miocene  epoch;  but  in 
deposits  belonging  to  the  middle  of  that  epoch  its 
place  is  taken  by  two  other  genera,  ffijyjmrion  and 
Anchitlierium ;  ^  and,  in  the  lowest  Miocene  and 
upper  Eocene,  only  the  last  genus  occurs.  A 
species  of  Anchitlierium  was  referred  by  Cuvier  to 
the  Palceotheria  under  the  name  of  P.  aurelianense. 
The  grinding-teeth  are  in  fact  very  similar  in 
shape  and  in  pattern,  and  in  the  absence  of  any 
thick  layer  of  cement,  to  those  of  some  species  of 
Paloeotherium,  especially  Cuvier's  Palceotherium 
minus,  which  has  been  formed  into  a  separate 
genus,  Plagiolophus,  by  Pomel.  But  in  the  fact 
that  there  are  only  six  full-sized  grinders  in  the 
lower  jaw,  the  first  premolar  being  very  small; 
that  the  anterior  grinders  are  as  large  as,  or 
rather  larger  than,  the  posterior  ones ;  that  the 

^  Heniiann  von  Meyer  gave  the  name  of  Anchitherium  to  A. 
Ezquerrce  ;  and  in  his  paper  on  the  subject  he  takes  great  pains 
to  distinguish  the  latter  as  the  type  of  a  new  genus,  from 
Cuvier's  Palceothe?'iu7n  d' Orleans.  But  it  is  precisely  the 
Palceotherium  d'Orleans  Avhich  is  the  type  of  Christol's  genus 
Hipparitherhcm  ;  and  thus,  though  Hipi'^riihcrium  is  of  later 
date  than  Anchitherium,  it  seemed  to  me  to  have  a  sort  of 
equitable  right  to  recognition  when  this  Address  was  written. 
On  the  whole,  however,  it  seems  most  convenient  to  adopt 
Anchitherium. 


856  PALiEONTOLOGY   AND   EVOLUTION  xi 

second  premolar  has  an  anterior  prolongation ;  and 
that  the  posterior  molar  of  the  lower  jaw  has,  as 
Cuvier  pointed  out,  a  posterior  lobe  of  much 
smaller  size  and  different  form,  the  dentition  of 
Anchitherium  departs  from  the  type  of  the 
Palceotherium,  and  approaches  that  of  the  Horse. 

Again,  the  skeleton  of  Anchitherium  is  ex- 
tremely equine.  M.  Christol  goes  so  far  as  to 
say  that  the  description  of  the  bones  of  the  horse, 
or  the  ass,  current  in  veterinary  works,  would  fit 
those  of  AncJiitherium.  And,  in  a  general  way, 
this  may  be  true  enough ;  but  there  are  some  most 
important  differences,  which,  indeed,  are  justly 
indicated  by  the  same  careful  observer.  Thus  the 
ulna  is  complete  throughout,  and  its  shaft  is  not  a 
mere  rudiment,  fused  into  one  bone  with  the 
radius.  There  are  three  toes,  one  large  in  the 
middle  and  one  small  on  each  side.  The  femur  is 
quite  like  that  of  a  horse,  and  has  the  character- 
istic fossa  above  the  external  condyle.  In  the 
British  Museum  there  is  a  most  instructive 
specimen  of  the  leg-bones,  showing  that  the  fibula 
was  represented  by  the  external  malleolus  and  by 
a  flat  tongue  of  bone,  which  extends  up  from  it 
on  the  outer  side  of  the  tibia,  and  is  closely 
ankylosed  with  the  latter  bone.^     The  hind  toes 

^  I  am  indebted  to  M.  Gervais  for  a  specimen  which  indicates 
that  the  fibula  v/as  complete,  at  any  rate,  in  some  cases  ;  and 
for  a  very  interesting  ramus  of  a  mnndible,  -which  shows  that, 
as  in  the  Palccothcria,  the  hindermost  milk-molar  of  the  lowei 


XI  PALEONTOLOGY   AXD   EVOLUTION  857 

are  three,  like  those  of  the  fore  leg;  and  the 
middle  metatarsal  bone  is  much  less  compressed 
from  side  to  side  than  that  of  the  horse. 

In  the  Hi^ppariorij  the  teeth  nearly  resemble 
those  of  the  Horses,  though  the  crowns  of  the 
grinders  are  not  so  long ;  like  those  of  the  Horses, 
they  are  abundantly  coated  with  cement.  The 
shaft  of  the  ulna  is  reduced  to  a  mere  style,  anky- 
losed  throughout  nearly  its  whole  length  with  the 
radius,  and  appearing  to  be  little  more  than  a 
ridge  on  the  surface  of  the  latter  bone  until  it  is 
carefully  examined.  The  front  toes  are  still  three, 
but  the  outer  ones  are  more  slender  than  in 
Anchitherium,  and  their  hoofs  smaller  in  proportion 
to  that  of  the  middle  toe ;  they  are,  in  fact,  re- 
duced to  mere  dew-claws,  and  do  not  touch  the 
ground.  In  the  leg,  the  distal  end  of  the  fibula  is 
so  completely  united  with  the  tibia  that  it  appears 
to  be  a  mere  process  of  the  latter  bone,  as  in  the 
Horses. 

In  Equus,  finally,  the  crowns  of  the  grinding- 
teeth  become  longer,  and  their  patterns  are  slightly 
modified ;  the  middle  of  the  shaft  of  the  ulna 
usually  vanishes,  and  its  proximal  and  distal  ends 
ankylose  with  the  radius.  The  phalanges  of  the 
two  outer  toes  in  each  foot  disappear,  their  meta- 
carpal and  metatarsal  bones  being  left  as  the 
«  sphnts." 

jaw  was  devoid  of  the  posterior  lobe  which  exists  in  the  hinder* 
most  triie  molar. 


358  PALEONTOLOGY  AND   EVOLUTION  xi 

The  Hipparion  has  large  depressions  on  the 
face  in  front  of  the  orbits,  Hke  those  for  the 
"  larmiers  "  of  many  ruminants ;  but  traces  of  these 
are  to  be  seen  in  some  of  the  fossil  horses  from 
the  Sewalik  EQlls;  and,  as  Leidy's  recent  re- 
searches show,  they  are  preserved  in  Anchi- 
therium. 

When  we  consider  these  facts,  and  the  further 
circumstance  that  the  Hipparions,  the  remains  of 
which  have  been  collected  in  immense  numbers, 
were  subject,  as  M.  Gaudry  and  others  have 
pointed  out,  to  a  great  range  of  variation,  it 
appears  to  me  impossible  to  resist  the  conclusion 
that  the  types  of  the  Anchithcriiim,  of  the 
Jlipparion,  and  of  the  ancient  Horses  consti- 
tute the  Hneage  of  the  modern  Horses,  the  Jlip- 
parion being  the  intermediate  stage  between  the 
other  two,  and  answering  to  B  in  my  foiTQer 
illustration. 

The  process  by  which  the  Anchitherium  has 
been  converted  into  Equus  is  one  of  specialisation, 
or  of  more  and  more  complete  deviation  from  what 
might  be  called  the  average  form  of  an  ungulate 
mammal.  In  the  Horses,  the  reduction  of  some 
parts  of  the  limbs,  together  with  the  special  modi- 
fication of  those  which  are  left,  is  carried  to  a 
greater  extent  than  in  any  other  hoofed  mammals. 
The  reduction  is  less  and  the  specialisation  is  less 
in  the  Hipparion,  and  still  less  in  the  Anchi- 
therium ;  but  yet,  as  compared  with  other  mam- 


XI  PALEONTOLOGY  AND   EVOLUTION  359 

mals,  the  reduction  and  specialisation  of  parts  in 
the  Anchitherium  remain  great. 

Is  it  not  probable  then,  that,  just  as  in  the 
Miocene  epoch,  we  find  an  ancestral  equine  form 
less  modified  than  Uqtms,  so,  if  we  go  back 
to  the  Eocene  epoch,  we  shall  find  some  quadruped 
related  to  the  Anchitherium,  as  Hipparion  is  re- 
lated to  Eqious,  and  consequently  departing  less 
from  the  average  form  ? 

I  think  that  this  desideratum  is  very  nearly,  if 
not  quite,  supplied  by  Flagiolophtts,  remains  of 
which  occur  abundantly  in  some  parts  of  the 
Upper  and  Middle  Eocene  formations.  The 
patterns  of  the  grinding-teeth  of  Plagiolcphus  are 
similar  to  those  of  Anchitherium,  and  their  crowns 
are  as  thinly  covered  with  cement;  but  the 
grinders  diminish  in  size  forwards,  and  the  last 
lower  molar  has  a  large  hind  lobe,  convex  outwards 
and  concave  inwards,  as  in  Falceotherium..  The 
ulna  is  complete  and  much  larger  than  in  any  of 
the  Equidce,  while  it  is  more  slender  than  in  most 
of  the  true  Palceotheria ;  it  is  fixedly  united,  but 
not  ankylosed,  with  the  radius.  There  are  three 
toes  in  the  fore  limb,  the  outer  ones  being  slender, 
but  less  attenuated  than  in  the  Equiclce.  The 
femur  is  more  like  that  of  the  Palceotheria  than 
that  of  the  horse,  and  has  only  a  small  depression 
above  its  outer  condyle  in  the  place  of  the  gTeat 
fossa  which  is  so  obvious  in  the  Pquidce.  The  fibula 
is  distinct,  but  very  slender,  and  its  distal  end  is 


360  PALEONTOLOGY   AND   EVOLUTION  XI 

ankjdosed  with  the  tibia.  There  are  three  toes 
on  the  hind  foot  having  similar  proportions  to 
those  on  the  fore  foot.  The  principal  metacarpal 
and  metatarsal  bones  are  flatter  than  they  are  in 
any  of  the  Equidce  ;  and  the  metacarpal  bones  are 
longer  than  the  metatarsals,  as  in  the  Palceothcria. 
■  In  its  general  form,  PlagioloijJius  resembles  a 
very  small  and  slender  horse,^  and  is  totally  unlike 
the  reluctant,  pig-like  creature  depicted  in  Cuvier's 
restoration  of  his  Palceotlurium  minus  in  the 
"  Ossemens  Fossiles." 

It  would  be  hazardous  to  say  that  PlagiolopTius 
is  the  exact  radical  form  of  the  Equine  quadru- 
peds; but  I  do  not  think  there  can  be  any 
reasonable  doubt  that  the  latter  animals  have 
resulted  from  the  modification  of  some  quadruped 
similar  to  Plagiolophus. 

We  have  thus  arrived  at  the  Middle  Eocene 
formation,  and  yet  have  traced  back  the  Horses 
only  to  a  three-toed  stock ;  but  these  three-toed 
forms,  no  less  than  the  Equine  quadrupeds  them- 
selves, present  rudiments  of  the  two  other  toes 
which  appertain  to  what  I  have  termed  the 
"  average  "  quadruped.  If  the  expectation  raised 
by  the  splints  of  the  Horses  that,  in  some  ancestor 
of  the  Horses,  these  splints  would  be  found  to 
be  complete  digits,  has  been  verified,  we  are  fur- 

^  Such,  at  least,  is  the  conclusion  sugo^ested  by  the  proportions 
of  the  skeleton  figured  by  Cuvier  and  De  Blainville  ;  but  per- 
haps something  between  a  Horse  and  an  Agouti  would  be  nearest 
the  mark. 


XI  PALAEONTOLOGY  AND   EVOLUTION  861 

nished  with  very  strong  reasons  for  looking  for  a 
no  less  complete  verification  of  the  expectation 
that  the  three-toed  FlagiolojjJitcs-like  "  avus  "  of  the 
horse  must  have  had  a  five-toed  "  atavus  "  at  some 
earlier  period. 

No  such  five-toed  "  atavus,"  however,  has  yet 
made  its  appearance  among  the  few  middle  and 
older  Eocene  Mammalia  which  are  known. 

Another  series  of  closely  affiliated  forms,  though 
the  evidence  they  afford  is  perhaps  less  complete 
than  that  of  the  Equine  series,  is  presented  to 
us  by  the  Diclwhune  of  the  Eocene  epoch,  the 
Cainctherium  of  the  Miocene,  and  the  Tragulidce, 
or  so-called  "  Musk-deer,"  of  the  present  day. 

The  Tragulidm  have  no  incisors  in  the  upper 
jaw,  and  only  six  grinding-teeth  on  each  side  of 
each  jaw ;  while  the  canine  is  moved  up  to  the 
outer  incisor,  and  there  is  a  diastema  in  the  lower 
jaw.  There  are  four  complete  toes  on  the  hind 
foot,  but  the  middle  metatarsals  usually  become, 
sooner  or  later,  ankylosed  into  a  cannon  bone. 
The  navicular  and  the  cuboid  unite,  and  the 
distal  end  of  the  fibula  is  ankylosed  with  the 
tibia. 

In  Cainctherium  and  Dichchune  the  upper 
incisors  are  fully  developed.  There  are  seven 
grinders ;  the  teeth  form  a  continuous  series  with- 
out a  diastema.  The  metatarsals,  the  navicular 
and  cuboid,  and  the  distal  end  of  the  fibula, 
remain  free.     In  the  Cainctheriicm,  also,  the  second 


362  PALEONTOLOGY  AND  EVOLUTION  xi 

metacarpal  is  developed,  but  is  much  shorter  than 
the  third,  while  the  fifth  is  absent  or  rudimentary. 
In  this  respect  it  resembles  Anoplotherium  secimda^ 
rium.  This  circumstance,  and  the  peculiar  pattern 
of  the  upper  molars  in  Caincthcrium,  lead  me  to 
hesitate  in  considering  it  as  the  actual  ancestor 
of  the  modern  Tragulidce.  If  Diclioliune  has  a 
fore-toed  fore  foot  (though  I  am  inclined  to 
suspect  that  it  resembles  Caincther,iu7n),  it  will 
be  a  b'etter  representative  of  the  oldest  forms  of 
the  Traguline  series  ;  but  Dichchune  occurs  in  the 
Middle  Eocene,  and  is,  in  fact,  the  oldest  known 
artiodactyle  mammal.  Where,  then,  must  we 
look  for  its  five-toed  ancestor  ? 

If  we  follow  down  other  lines  of  recent  and 
tertiary  Ungidata,  the  same  question  presents 
itself.  The  Pigs  are  traceable  back  through  the 
Miocene  epoch  to  the  Upper  Eocene,  where  they 
appear  in  the  two  well-marked  forms  of  Hyopopo- 
tamus  and  Chmropotamus ;  but  Hyojpotamus  appears 
to  have  had  only  two  toes. 

Again,  all  the  great  groups  of  the  Ruminants, 
the  Bovidoe,  Antilcpidoe,  Camelopardcdidce,  and 
Cewidce,  are  represented  in  the  Miocene  epoch,  and 
so  are  the  Camels.  The  Upper  Eocene  Anc^jlo' 
therium,  which  is  intercalary  between  the  Pigs 
and  the  Tragulidce,  has  only  two,  or,  at  most, 
three  toes.  Among  the  scanty  mammals  of  the 
Lower  Eocene  formation  we  have  the  perisso- 
dactyle     Ungulata    rej)resented    by    Coryphcdon^ 


XI  PALEONTOLOGY  AND   EVOLUTION  863 

Kyracotherium,  and  Fliolophus.  Suppose  for  a 
moment,  for  tlie  sake  of  following  out  the 
argument,  that  Flioloj^htcs  represents  the  primary 
stock  of  the  Perissodactyles,  and  Dichohune  that 
of  the  Artiodactyles  (though  I  am  far  from  saying 
that  such  is  the  case),  then  we  find,  in  the  earliest 
fauna  of  the  Eocene  epoch  to  which  our  investiga- 
tions carry  us,  the  two  divisions  of  the  Ungulata 
completely  differentiated,  and  n)  trace  of  any 
common  stock  of  both,  or  of  hve-toed  predecessors 
to  either.  With  the  case  of  the  Horses  before  us, 
justifying  a  belief  in  the  production  of  new 
animal  forms  by  modification  of  old  ones,  I  see  no 
escape  from  the  necessity  of  seeking  for  these 
ancestors  of  the  Ungulata  beyond  the  limits  of 
the  Tertiary  formations. 

I  could  as  soon  admit  special  creation,  at 
once,  as  suppose  that  the  Perissodactyles  and 
Artiodactyles  had  no  five- toed  ancestors.  And 
when  we  consider  how  large  a  portion  of  the 
Tertiary  period  elapsed  before  Anchithermm  was 
converted  into  Uquus,  it  is  difficult  to  escape  the 
conclusion  that  a  large  proportion  of  time  anterior 
to  the  Tertiary  period  must  have  been  expended 
in  converting  the  common  stock  of  the  Ungulata 
into  Perissodactyles  and  Artiodactyles. 

The  same  moral  is  inculcated  by  the  study 
of  every  other  order  of  Tertiary  monodelphous 
Mammalia.  Each  of  these  orders  is  represented 
in  the  Miocene  epoch :  the  Eocene  formation,  as 


864  PALiEONTOLOGY  AND   EVOLUTION  xi 

I  have  already  said,  contains  Cheircptera,  Inscdi- 
vora,  Bodentia,  Ungulata,  Carnivora,  and  Cetacea, 
But  the  CheivGiJtera  are  extreme  modifications 
of  the  Insectivora,  just  as  the  Cdacea  are  extreme 
modifications  of  the  Carnivorous  t}^e  ;  and  there- 
fore it  is  to  my  mind  incredible  that  monodelphous 
Inscctivora  and  Carnivora  should  not  have  been 
abundantly  developed,  along  with  Ungidata,  in 
the  Mesozoic  epoch.  But  if  this  be  the  case, 
how  much  further  back  must  we  go  to  find  the 
common  stock  of  the  monodelphous  Mainmalia? 
As  to  the  Didelphia,  if  we  may  trust  the  evidence 
which  seems  to  be  afforded  by  their  very  scanty 
remains,  a  Hypsiprymnoid  form  existed  at  the 
epoch  of  the  Trias,  contemporaneously  with  a 
Carnivorous  form.  At  the  epoch  of  the  Trias, 
therefore,  the  Marsiiiyialia  must  have  already 
existed  long  enough  to  have  become  differentiated 
into  carnivorous  and  herbivorous  forms.  But  the 
Monotremata  are  lower  forms  than  the  Didelphia 
which  last  are  intercalary  between  the  Ornitho- 
delphia  and  the  Moncddphia.  To  what  point  of 
the  Palaeozoic  epoch,  then,  must  we,  upon  any 
rational  estimate,  relegate  the  origin  of  the 
Monotremata  ? 

The  investigation  of  the  occurrence  of  the 
classes  and  of  the  orders  of  the  Sauropsida  in  time 
points  in  exactly  the  same  direction.  If,  as  there 
is  great  reason  to  believe,  true  Birds  existed  in 
the  Triassic  epoch,  the  ornithoscelidous  forms  by 


XI  PALEONTOLOGY   AND   EVOLUTION  865 

whicti  Reptiles  passed  into  Birds  must  have  pre- 
ceded them.  In  fact  there  is,  even  at  present, 
considerable  ground  for  suspecting  the  existence 
of  Binoscmria  in  the  Permian  formations ;  but,  in 
that  case,  lizards  must  be  of  still  earlier  date. 
And  if  the  very  small  differences  which  are 
observable  between  the  Crocodilia  of  the  older 
Mesozoic  formations  and  those  of  the  present  day 
furnish  any  sort  of  approximation  toAvards  an 
estimate  of  the  average  rate  of  change  among  the 
Sauropsida,  it  is  almost  appalling  to  reflect  how  far 
back  in  Palaeozoic  times  we  must  go,  before  we 
can  hope  to  arrive  at  that  common  stock  from 
which  the  Crocodilia,  Lacertilia,  Ornithoscdida, 
and  Flesiosauria,  which  had  attained  so  great  a 
development  in  the  Triassic  epoch,  must  have 
been  derived. 

The  Amphibia  and  Pisces  tell  the  same  story. 
There  is  not  a  single  class  of  vertebrated  animals 
which,  when  it  first  appears,  is  represented  by 
analogues  of  the  lowest  known  members  of  the 
same  class.  Therefore,  if  there  is  any  truth  in 
the  doctrine  of  evolution,  every  class  must  be  vastly 
older  than  the  first  record  of  its  appearance  upon 
the  surface  of  the  globe.  But  if  considerations  of 
this  kind  compel  us  to  place  the  origin  of  ver- 
tebrated animals  at  a  period  sufficiently  distant 
from  the  Upper  Silurian,  in  which  the  first  Elas- 
mobranchs  and  Ganoids  occur,  to  allow  of  the 
evolution  of  such  fishes  as  these  firom  a  Vertebrate 


366  PALEONTOLOGY   AND   EVOLUTION  xi 

as  simple  as  the  Ampliioxus,  I  can  only  repeat 
that  it  is  appalling  to  speculate  upon  the  extent 
to  which  that  origin  must  have  preceded  the 
epoch  of  the  first  recorded  appearance  of  verte- 
brate life. 


Such  is  the  further  commentary  which  I  have 
to  offer  upon  the  statement  of  the  chief  results  of 
palseontology  which  I  formerly  ventured  to  lay 
before  you. 

But  the  growth  of  knowledge  in  the  interval 
makes  me  conscious  of  an  omission  of  considerable 
moment  in  that  statement,  inasmuch  as  it  contains 
no  reference  to  the  bearings  of  palseontology  upon 
the  theory  of  the  distribution  of  Hfe;  nor  takes 
note  of  the  remarkable  manner  in  which  the  facts 
of  distribution,  in  present  and  past  times,  accord 
with  the  doctrine  of  evolution,  especially  in  regard 
to  land  animals. 

That  connection  between  palseontology  and 
geology  and  the  present  distribution  of  terrestrial 
animals,  which  so  strikingly  impressed  Mr.  Darwin, 
thirty  years  ago,  as  to  lead  him  to  speak  of  a  "  law 
of  succession  of  types,"  and  of  the  wonderful  re- 
lationship on  the  same  continent  between  the 
dead  and  the  living,  has  recently  received  much 
elucidation  from  the  researches  of  Gaudry,  of 
Rutimeyer,  of  Leidy,  and  of  Alphonse  Milne- 
Edwards,  taken  in  connection  with  the  earlier 
labours  of  our  lamented  colleague  Falconer;  and 


XI  PALEONTOLOGY   AND   EVOLUTION  867 

it  has  been  instructively  discussed  in  the  thought- 
ful and  ingenious  work  of  Mr.  Andrew  Murray 
"  On  the  Geographical  Distribution  of  Mammals."  ^ 

I  propose  to  lay  before  you,  as  briefly  as  I  can, 
the  ideas  to  which  a  long  consideration  of  the 
subject  has  given  rise  in  my  mind. 

If  the  doctrine  of  evolution  is  sound,  one  of  its 
immediate  consequences  clearly  is,  that  the  present 
distribution  of  life  upon  the  globe  is  the  product 
of  two  factors,  the  one  being  the  distribution 
which  obtained  in  the  immediately  preceding 
epoch,  and  the  other  the  character  and  the  extent 
of  the  changes  which  have  taken  place  in  physical 
geography  between  the  one  epoch  and  the  other ; 
or,  to  put  the  matter  in  another  way,  the  Fauna 
and  Flora  of  any  given  area,  in  any  given  epoch, 
can  consist  only  of  such  forms  of  life  as  are  directly 
descended  from  those  which  constituted  the  Fauna 
and  Flora  of  the  same  area  in  the  immediately 
preceding  epoch,  unless  the  physical  geography 
(under  which  I  include  climatal  conditions)  of 
the  area  has  been  so  altered  as  to  give  rise  to 
immigration  of  living  forms  from  some  other 
area. 

The  evolutionist,  therefore,  is  bound  to  grapple 

^  The  paper  * '  On  the  Form  and  Distribution  of  the  Land- 
tracts  during  the  Secondary  and  Tertiary  Periods  respectively  ; 
and  on  the  Effect  upon  Animal  Life  M'hich  great  Changes  m 
Geograpliical  Configuration  have  probably  produced,"  by  Mr. 
Searles  V.  Wood,  jun.,  which  was  published  in  th.Q  Philosophical 
Magazine,  in  1862,  was  unknown  to  me  when  this  Address 
Was  written.     It  is  well  worthy  of  the  most  careful  study. 


368  PALEONTOLOGY   AND   EVOLUTION  xi 

with  the  following  problem  whenever  it  is  clearly 
put  before  him  : — Here  are  the  Faunae  of  the  same 
area  during  successive  epochs.  Show  good  cause 
for  believing  either  that  these  Faunae  have  been 
derived  from  one  another  by  gradual  modification, 
or  that  the  Faunae  have  reached  the  area  in  ques- 
tion by  migration  from  some  area  in  which  they 
have  undergone  their  development. 

I  propose  to  attempt  to  deal  with  this  problem, 
so  far  as  it  is  exemplified  by  the  distribution  of 
the  terrestrial  Vertchrata,  and  I  shall  endeavour 
to  show  you  that  it  is  capable  of  solution  in  a 
sense  entirely  favourable  to  the  doctrine  of  evo- 
hition. 

I  have  elsewhere  ^  stated  at  length  the  reasons 
which  lead  me  to  recognise  four  primary  distribu- 
tional provinces  for  the  terrestrial  Vertchrata  in 
the  present  world,  namely, — first,  the  Ncvozelanian, 
or  New-Zealand  province ;  secondly,  the  Austra- 
lian province,  including  Australia,  Tasmania,  and 
the  Negrito  Islands ;  thirdly,  Aitstro-Cohtnibia,  or 
South  America  plus  North  America  as  far  as 
Mexico ;  and  fourthly,  the  rest  of  the  world,  or 
Ardoga^a,  in  which  province  America  north  of 
Mexico  constitutes  one  sub-province,  Africa  south 
of  the  Sahara  a  second,  Hindostan  a  third,  and  the 
remainder  of  the  Old  World  a  fourth. 

Now  the  truth  which  Mr.  Darwin  perceived  and 

1  "  On  the  Classification  and  Distribution  of  the  Alectoro- 
morphfe  ;  "  Proceedings  of  the  Zoological  itociriy,  1868. 


XI  PALEONTOLOGY  AND  EVOLUTION  369 

promulgated  as  "the  law  of  tlie  succession  of 
types  "  is,  that,  in  all  these  provinces,  the  animals 
found  in  Pliocene  or  later  deposits  are  closely 
affined  to  those  which  now  inhabit  the  same  pro- 
vinces ;  and  that,  conversely,  the  forms  character- 
istic of  other  provinces  are  absent.  North  and 
South  America,  perhaps,  present  one  or  two 
exceptions  to  the  last  rule,  but  they  are  readily 
susceptible  of  explanation.  Thus,  in  Australia,  the 
later  Tertiary  mammals  are  marsupials  (possibly 
with  the  exception  of  the  Dog  and  a  Rodent  or  two, 
as  at  present).  In  Austro-Columbia,  the  later 
Tertiary  fauna  exhibits  numerous  and  varied  forms 
of  Platyrrhine  Apes,  Rodents,  Cats,  Dogs,  Stags, 
Edentata,  and  Opossums ;  but,  as  at  present,  no 
Catarrhine  Apes,  no  Lemurs,  no  Insectivora,  Oxen, 
Antelopes,  Rhinoceroses,  nor  Didelphia  other  than 
Opossums.  And  in  the  widespread  Arctogseal 
province,  the  Pliocene  and  later  mammals  belong 
to  the  same  gi'oups  as  those  which  now  exist  in 
the  province.  The  law  of  succession  of  types^ 
therefore,  holds  good  for  the  present  epoch  as 
compared  with  its  predecessor.  Does  it  equally 
well  apply  to  the  Pliocene  fauna  when  we  com- 
pare it  with  that  of  the  Miocene  epoch  ?  By 
great  good  fortune,  an  extensive  mammalian  fauna 
of  the  latter  epoch  has  now  become  known,  in 
four  very  distant  portions  of  the  Arctogseal  pro- 
vince which  do  not  differ  greatly  in  latitude. 
Thus  Falconer  and  Cautley  have  made  known  the 

210 


370  PALEONTOLOGY   AND   EVOLUTION  xi 

fauna  of  the  sub-Himalayas  and  the  Perim  Islands  ; 
Gaudry  that  of  Attica ;  many  observers  that  of 
Central  Europe  and  France ;  and  Leidy  that  of 
Nebraska,  on  the  eastern  flank  of  the  Rocky 
Mountains.  The  results  are  very  striking.  The 
total  Miocene  fauna  comprises  many  genera  and 
species  of  Catarrhine  Apes,  of  Bats,  of  Insectivora ; 
of  Arctog^eal  t}^es  of  Pvodentia ;  oi  Frohoscidea  ;  of 
equine,  rhinocerotic,  and  tapirine  quadrupeds  ;  of 
cameline,  bovine,  antilopine,  cervine,  and  traguline 
Ruminants;  of  Pigs  and  Hippopotamuses;  of 
Viverridcc  and  Hycenidce  among  other  Carnivora  ; 
with  Edentata  allied  to  the  Arctogseal  Oryderopus 
and  Maiiis,  and  not  to  the  Austro-Columbian 
Edentates.  The  only  type  present  in  the  Miocene 
but  absent  in  the  existing,  fauna  of  Eastern  Arc- 
togaea,  is  that  of  the  Dideli^liidce,  which,  however, 
remains  in  North  America. 

But  it  is  very  remarkable  that  while  the 
Miocene  fauna  of  the  Arctog^al  province,  as 
a  whole,  is  of  the  same  character  as  the  existing 
fauna  of  the  same  province,  as  a  whole,  the  com- 
ponent elements  of  the  fauna  were  differently  as- 
sociated. In  the  Miocene  epoch.  North  America 
possessed  Elephants,  Horses,  Rhinoceroses,  and  a 
great  number  and  variety  of  Ruminants  and  Pigs, 
which  are  absent  in  the  present  indigenous  fauna; 
Europe  had  its  Apes,  Elephants,  Rhinoceroses, 
Tapirs,  Musk-deer,  Giraffes,  Hyaenas,  great  Cats, 
Edentates,   and    Opossum-like  Marsupials,   which 


XI 


PALJiONTOLOGY   AND    EVOLUTION  371 


have  equally  vanished  from  its  present  fauna ; 
and  in  Northern  India,  the  African  types  of  Hippo- 
potamuses, Giraffes,  and  Elephants  were  mixed 
up  with  what  are  now  the  Asiatic  ty^es  of  the 
latter,  and  with  Camels,  and  Semnopithecine  and 
Pithecine  Apes  of  no  less  distinctly  Asiatic  forms. 
In  fact  the  Miocene  mammalian  fauna  of 
Europe  and  the  Himalayan  regions  contains,  asso- 
ciated together,  the  types  which  are  at  present 
separately  located  in  the  South- African  and 
Indian  sub-provinces  of  Arctogsea.  Now  there 
is  every  reason  to  believe,  on  other  grounds,  that 
both  Hindostan,  south  of  the  Ganges,  and  Africa, 
south  of  the  Sahara,  were  separated  by  a  wide 
sea  from  Europe  and  North  Asia  during  the 
Middle  and  Upper  Eocene  epochs.  Hence  it 
becomes  highly  probable  that  the  well-known 
similarities,  and  no  less  remarkable  differences 
between  the  present  Faunae  of  India  and  South 
Africa  have  arisen  in  some  such  fashion  as  the 
following.  Some  time  during  the  Miocene  epoch, 
possibly  when  the  Himalayan  chain  was  ele- 
vated, the  bottom  of  the  nummulitic  sea  was 
upheaved  and  converted  into  dry  land,  in  the 
direction  of  a  line  extending  from  Abyssinia  to 
the  mouth  of  the  Ganges.  By  this  means,  the 
Dekhan  on  the  one  hand,  and  South  Africa  on 
the  other,  became  connected  with  the  Miocene 
dry  land  and  with  one  another.  The  Miocene 
mammals  spread  gradually  over  this  intermediate 


872  PALAEONTOLOGY    AND   EVOLUTION  xi 

dry  land ;  and  if  the  condition  of  its  eastern  and 
western  ends  offered  as  wide  contrasts  as  the 
valleys  of  the  Ganges  and  Arabia  do  now,  many 
forms  which  made  their  way  into  Africa  must 
have  been  different  from  those  which  reached 
the  Dekhan,  while  others  might  pass  into  both 
these  sub-provinces. 

That  there  was  a  continuity  of  dry  land  between 
Europe  and  North  America  during  the  Miocene 
epoch,  appears  to  me  to  be  a  necessary  consequence 
of  the  fact  that  many  genera  of  terrestrial 
mammals,  such  as  Castor,  Hystrix,  Mephas, 
Mastodon,  Uquus,  Hipparion,  AncMtJieriitm,  Rhino- 
ceros, Cervus,  AmpMcyon,  Hycenarctos,  and  Machair- 
odus,  are  common  to  the  Miocene  formations  of 
the  two  areas,  and  have  as  yet  been  found  (except 
perhaps  Anchitherium)  in  no  deposit  of  earlier  age. 
Whether  this  connection  took  place  by  the  east, 
or  by  the  west,  or  by  both  sides  of  the  Old 
World,  there  is  at  present  no  certain  evidence,  and 
the  question  is  immaterial  to  the  present  argu- 
ment; but,  as  there  are  good  grounds  for  the 
belief  that  the  Australian  province  and  the  Indian 
and  South- African  sub-provinces  were  separated 
by  sea  from  the  rest  of  Arctogsea  before  the 
Miocene  epoch,  so  it  has  been  rendered  no  less 
probable,  by  the  investigations  of  Mr.  Canick 
Moore  and  Professor  Duncan,  that  Austro-Columbia 
was  separated  by  sea  from  North  America  during 
a  large  part  of  the  Miocene  epoch. 


XI  PALEONTOLOGY  AND    EVOLUTION  873 

It  is  unfortunate  that  we  have  no  knowledge  oF 
the  Miocene  mammalian  fauna  of  the  Australian 
and  Austro-Columbian  provinces ;  but,  seeing  that 
not  a  trace  of  a  Platyrrhine  Ape,  of  a  Procyonine 
Carnivore,  of  a  characteristically  South-American 
Rodent,  of  a  Sloth,  an  Armadillo,  or  an  Ant-eater 
has  yet  been  found  in  Miocene  deposits  of  Arc- 
tog^a,  I  cannot  doubt  that  they  already  existed  in 
the  Miocene  Austro-Columbian  province. 

.  Nor  is  it  less  probable  that  the  characteristic 
types  of  Australian  Mammalia  were  already  de- 
veloped in  that  region  in  Miocene  times. 

But  Austro-Columbia  presents  difficulties  from 
which  Australia  is  free ;  Camelidce  and  Tapiridce 
are  now  indigenous  in  South  America  as  they  are 
in  Arctogsea;  and,  among  the  Pliocene  Austro- 
Columbian  mammals,  the  Arctoggeal  genera 
Equus,  Mastodon,  and  Machairodus  are  numbered. 
Are  these  Postmiocene  immigrants,  or  Praemio- 
cene  natives  ? 

Still  more  perplexing  are  the  strange  and  in- 
teresting forms  Toxodon,  Macrauchenm,  Typo- 
therium,  and  a  new  Anoplotherioid  mammal 
{Homalodotherium)  which  Dr.  Cunningham  sent 
over  to  me  some  time  ago  from  Patagonia.  I  con- 
fess I  am  strongly  inclined  to  surmise  that  these 
last,  at  any  rate,  are  remnants  of  the  popula- 
tion of  Austro-Columbia  before  the  Miocene 
epoch,  and  were  not  derived  from  Arctogaea  by 
way  of  the  north  and  east 


874  PALEONTOLOGY  AND   EVOLUTION  XI 

The  fact  that  this  immense  fauna  of  Miocene 
Arctogaea  is  now  fully  and  richly  represented  only 
in  India  and  in  South  Africa,  while  it  is  shrunk 
and    depauperised   in   North   Asia,   Europe,  and 
North  America,  becomes  at  once  intelligible,  if  we 
suppose  that  India  and  South  Africa  had  but  a 
scanty  mammalian  population  before  the  Miocene 
immigration,  while    the    conditions   were  highly 
favourable  to  the  new  comers.     It  is  to  be  supposed 
that  these  new  regions  offered  themselves  to  the 
Miocene  Ungulates,  as  South  America  and  Australia 
offered  themselves  to  the  cattle,  sheep,  and  horses 
of  modern  colonists.     But,  after  these  great  areas 
were  thus  peopled,  came  the  Glacial  epoch,  during 
which  the  excessive  cold,  to  say  nothing  of  depres- 
sion and  ice-covering,  must  have  almost  depopu- 
lated all  the  northern  parts  of  Arctogsea,  destroying 
all  the  higher   mammalian   forms,  except   those 
which,  like  the  Elephant  and  Rhinoceros,  could 
adjust  their  coats  to  the  altered  conditions.     Even 
these  must    have    been    driven   away  from    the 
greater  part  of  the   area;    only    those    Miocene 
mammals  which  had  passed  into  Hindostan  and 
into  South  Africa  would  escape  decimation  by  such 
changes  in  the  physical  geography  of  Arctogsea. 
And  when  the  northern  hemisphere  passed  into  its 
present  condition,  these  lost  tribes  of  the  Miocene 
Fauna    were    hemmed    by    the    Himalayas,    the 
Sahara,  the  Red  Sea,  and  the  Arabian  deserts, 
within  their  present  boundaries. 


XI 


PALEONTOLOGY  AND  EVOLUTION  875 


Now,  on  the  hypothesis  of  evolution,  there  is  no 
sort  of  difficulty  in  admitting  that  the  differences 
between  the  Miocene  forms  of  the  mammalian 
Fauna  and  those  which  exist  at  present  are  the 
results  of  gradual  modification;  and,  since  such 
differences  in  distribution  as  obtain  are  readily 
explained  by  the  changes  which  have  taken  place 
in  the  physical  geography  of  the  world  since  the 
Miocene  epoch,  it  is  clear  that  the  result  of  the 
comparison  of  the  Miocene  and  present  Faunae  is 
distinctly  in  favour  of  evolution.  Indeed  I  may 
go  further.  I  may  say  that  the  hypothesis  of 
evolution  explains  the  facts  of  Miocene,  Pliocene, 
and  Recent  distribution,  and  that  no  other  sup- 
position even  pretends  to  account  for  them.  It  is, 
indeed,  a  conceivable  supposition  that  every  species 
of  Rhinoceros  and  every  species  of  Hya3na,  in  the 
long  succession  of  forms  between  the  Miocene  and 
the  present  species,  was  separately  constructed  out 
of  dust,  or  out  of  nothing,  by  supernatural  power ; 
but  until  I  receive  distinct  evidence  of  the  fact,  I 
refuse  to  run  the  risk  of  insulting  any  sane  man 
by  supposing  that  he  seriously  holds  such  a 
notion. 

Let  us  now  take  a  step  further  back  in  time, 
and  inquire  into  the  relations  between  the  Miocene 
Fauna  and  its  predecessor  of  the  Upper  Eocene 
formation. 

Here  it  is  to  be  regretted  that  our  materials  for 
forming  a  judgment  are  nothing  to  be  compared 


876  PALEONTOLOGY   AND   EVOLUTION  xi 

in  point  of  extent  or  variety  with  those  which  are 
yielded  by  the  Miocene  strata.  However,  what  we 
do  know  of  this  Upper  Eocene  Fauna  of  Europe 
gives  sufficient  positive  information  to  enable  us 
to  draw  some  tolerably  safe  inferences.  It  has 
yielded  representatives  of  Inscdivora,  of  Cheir- 
o'pUra,  of  Bodentia,  of  Carnivora,  of  artiodactyle 
and  perissodactyle  Ungulata,  and  of  opossum-like 
Marsupials.  No  Australian  type  of  Marsupial  has 
been  discovered  in  the  Upper  Eocene  strata,  nor 
any  Edentate  mammal.  The  genera  (except  per- 
haps in  the  case  of  some  of  the  Inscdivora,  Cheir- 
cptera,  and  Rodentia)  are  different  from  those  of 
the  Miocene  epoch,  but  present  a  remarkable 
general  similarity  to  the  Miocene  and  recent 
genera.  In  several  cases,  as  I  have  already  shown, 
it  has  now  been  clearly  made  out  that  the  relation 
between  the  Eocene  and  Miocene  forms  is  such 
that  the  Eocene  form  is  the  less  specialised ;  while 
its  Miocene  ally  is  more  so,  and  the  specialisation 
reaches  its  maximum  in  the  recent  forms  of  the 
same  type. 

So  far  as  the  Upper  Eocene  and  the  Miocene 
Mammalian  Faunae  are  comparable,  their  relations 
are  such  as  in  no  way  to  oppose  the  hypothesis 
that  the  older  are  the  progenitors  of  the  more 
recent  forms,  while,  in  some  cases,  they  distinctly 
favour  that  h}^othesis!  The  period  in  time  and 
the  changes  in  physical  geography  represented  by 
the    nummulitic    dejiosits  are  undoubtedly   very 


XI  PALEONTOLOGY  AXD   EVOLUTION  377 

great,  while  the  remains  of  Middle  Eocene  and 
Older  Eocene  Mammals  are  comparatively  few. 
The  general  facies  of  the  Middle  Eocene  Fauna, 
however,  is  quite  that  of  the  Upper.  The  Older 
Eocene  pre-nummulitic  mammalian  Fauna  con- 
tains Bats,  two  genera  of  Carnivora,  three  genera 
of  Ungidatcc  (probably  all  perissodactyle),  and  a 
didelphid  Marsupial;  all  these  forms,  except 
perhaps  the  Bat  and  the  Opossum,  belong  to 
genera  which  are  not  known  to  occur  out  of  the 
Lower  Eocene  formation.  The  Coryphodcn  appears 
to  have  been  allied  to  the  Miocene  and  later 
Tapirs,  while  PliolopJius,  in  its  skull  and  dentition, 
curiously  partakes  of  both  artiodactyle  and  perisso- 
dactyle characters;  the  third  trochanter  upon 
its  femur  and  its  three-toed  hind  foot,  however, 
appear  definitely  to  fix  its  position  in  the  latter 
division. 

There  is  nothing,  then,  in  what  is  known  of  the 
older  Eocene  mammals  of  the  Arctogseal  province 
to  forbid  the  supposition  that  they  stood  m  an 
ancestral  relation  to  those  of  the  Calcaire  Grossier 
and  the  Gypsum  of  the  Paris  basin,  and  that  our 
present  fauna,  therefore,  is  directly  derived  from 
that  which  already  existed  in  Arctogsea  at  the 
commencement  of  the  Tertiary  period.  But  if 
we  now  cross  the  firontier  between  the  Cainozoic 
and  the  Mesozoic  faunae,  as  they  are  preserved 
within  the  Arctoggeal  area,  we  meet  with  an 
astounding    change,  and    what    appears   to   be  a 


378  PALiEONTOLOGY   AND   EVOLUTION  XT 

complete  and  unmistakable  break  in  the  line  of 
biological   continuity. 

Among  the  twelve  or  fourteen  species  of  Mam- 
malia which  are  said  to  have  been  found  in  the 
Parbecks,  not  one  is  a  member  of  the  orders 
Cheiroptera,  Bodentia,  Ungulata,  or  Carnivora, 
which  are  so  well  represented  in  the  Tertiaries. 
No  Tnsectivora  are  certainly  known,  nor  any 
opossum-like  Marsupials.  Thus  there  is  a  vast 
negative  difference  between  the  Cainozoic  and 
the  Mesozoic  mammalian  faunae  of  Europe.  But 
there  is  a  still  more  important  positive  difference, 
inasmuch  as  all  these  Mammaha  appear  to  be 
Marsupials  belonging  to  Australian  groups,  and 
thus  appertaining  to  a  different  distributional 
province  from  the  Eocene  and  Miocene  marsupials, 
which  are  Austro-Columbian.  So  far  as  the  im- 
perfect materials  which  exist  enable  a  judgment 
to  be  formed,  the  same  law  appears  to  have  held 
good  for  all  the  earlier  Mesozoic  Mammalia.  Of 
the  Stonesfield  slate  mammals,  one,  Amphither- 
ium,  has  a  definitely  Australian  character;  one, 
Fhascolotherium,  may  be  either  Dasyurid  or 
Didelphine  ;  of  a  third,  Stereo goiathus,  nothing 
can  at  present  be  said.  The  two  mammals 
of  the  Trias,  also,  appear  to  belong  to  Australian 
groups. 

Every  one  is  aware  of  the  many  curious  points 
of  resemblance  between  the  marine  fauna  of  the 
European  Mesozoic   rocks   and   that   which    now 


XI 


PALEONTOLOGY   AND   EVOLUTION  879 


exists  in  Australia.  But  if  there  was  this 
Australian  facies  about  both  the  terrestrial  and 
the  marine  faunae  of  Mesozoic  Europe,  and  if 
there  is  this  unaccountable  and  immense  break 
between  the  fauna  of  Mesozoic  and  that  of 
Tertiary  Europe,  is  it  not  a  very  obvious  sugges- 
tion that,  in  the  Mesozoic  epoch,  the  Australian 
province  included  Europe,  and  that  the  Arctogseal 
province  was  contained  within  other  limits  ?  The 
Arctogseal  province  is  at  present  enormous,  while 
the  Austrahan  is  relatively  small.  Why  should 
not  these  proportions  have  been  different  during 
the  Mesozoic  epoch  ? 

Thus  I  am  led  to  think  that  by  far  the  simplest 
and  most  rational  mode  of  accounting  for  the 
great  change  which  took  place  in  the  living 
inhabitants  of  the  European  area  at  the  end  of 
the  Mesozoic  epoch,  is  the  supposition  that  it 
arose  from  a  vast  alteration  of  the  physical 
geography  of  the  globe ;  whereby  an  area  long 
tenanted  by  Cainozoic  forms  was  brought  into 
such  relations  with  the  European  area  that 
migration  from  the  one  to  the  other  became 
possible,  and  took  place  on  a  great  scale. 

This  supposition  relieves  us,  at  once,  from  the 
difficulty  in  which  we  were  left,  some  time  ago, 
by  the  arguments  which  I  used  to  demonstrate 
the  necessity  of  the  existence  of  all  the  great 
types  of  the  Eocene  epoch  in  some  antecedent 
period. 


880  PIL^ONTOLOGT  AND   EVOLUTION  xi 

It  is  this  Mesozoic  continent  (which  may  well 
have  lain  in  the  neighbourhood  of  what  are  now 
the  shores  of  the  North  Pacific  Ocean)  which  I 
suppose  to  have  been  occupied  by  the  Mesozoic 
Monodeljpliia  ;  and  it  is  in  this  region  that  I  con- 
ceive they  must  have  gone  through  the  long 
series  of  changes  by  which  they  were  specialised 
into  the  forms  which  we  refer  to  different  orders. 
I  think  it  very  probable  that  what  is  now  South 
America  may  have  received  the  characteristic 
elements  of  its  mammalian  fauna  during  the 
Mesozoic  epoch ;  and  there  can  be  httle  doubt 
that  the  general  nature  of  the  change  which  took 
place  at  the  end  of  the  Mesozoic  epoch  in  Europe 
was  the  upheaval  of  the  eastern  and  northern 
regions  of  the  Mesozoic  sea-bottom  into  a  west- 
ward extension  of  the  Mesozoic  continent,  over 
which  the  mammalian  fauna,  by  which  it  was 
already  peopled,  gradually  spread.  This  invasion 
of  the  land  was  prefaced  by  a  previous  invasion  of 
the  Cretaceous  sea  by  modem  forms  of  mollusca 
and  fish. 

It  is  easy  to  imagine  how  an  analogous  change 
might  come  about  in  the  existing  world.  There 
is,  at  present,  a  great  difference  between  the  fauna 
of  the  Polynesian  Islands  and  that  of  the  west 
coast  of  America.  The  animals  which  are  leaving 
their  spoils  in  the  deposits  now  forming  in  these 
localities  are  widely  different.  Hence,  if  a  gradual 
shifting  of  the  deep  sea,  which   at  present  bars 


xr  PALEONTOLOGY  AND    EVOLUTION  381 

migration  between  the  easternmost  of  these  islands 
and  America,  took  place  to  the  westward,  while 
the  American  side  of  the  sea-bottom  was  gradually 
upheaved,  the  palaeontologist  of  the  future  would 
find,  over  the  Pacific  area,  exactly  such  a  change 
as  I  am  supposing  to  have  occurred  in  the  North- 
Atlantic  area  at  the  close  of  the  Mesozoic  period. 
An  Australian  fauna  would  be  found  underl}?ing 
an  American  fauna,  and  the  transition  from  the 
one  to  the  other  would  be  as  abrupt  as  that 
between  the  Chalk  and  lower  Tertiaries ;  and  as 
the  drainage-area  of  the  newly  formed  extension 
of  the  American  continent  gave  rise  to  rivers  and 
lakes,  the  mammals  mired  in  their  mud  would 
differ  from  those  of  like  deposits  on  the  Australian 
side,  just  as  the  Eocene  mammals  differ  from  those 
of  the  Purbecks. 

How  do  similar  reasonings  apply  to  the  other 
great  change  of  hfe — that  which  took  place  at  the 
end  of  the  Palaeozoic  period  ? 

In  the  Triassic  epoch,  the  distribution  of  the 
diy  land  and  of  terrestrial  vertebrate  life  appears 
to  have  been,  generally,  similar  to  that  which 
existed  in  the  Mesozoic  epoch ;  so  that  the  Triassic 
continents  and  their  faunae  seem  to  be  related  to  the 
Mesozoic  lands  and  their  faunae,  just  as  those  of  the 
Miocene  epoch  are  related  to  those  of  the  present 
day.  In  fact,  as  I  have  recently  endeavoured  to 
prove  to  the  Society,  there  was  an  Arctogaeal  con- 
tinent and  an  Arctogaeal  province  of  distribution 
in  Triassic  times  as  there  is  now  ;  and  the  Saurcp- 


382  PALEONTOLOGY   AND   EVOLUTION  il 

sida  and  Marsu2ncdia  which  constituted  that  fauna 
were,  I  doubt  not,  the  progenitors  of  the  Sauropsida 
and  Marsuinalia  of  the  whole  Mesozoic  epoch. 

Looking  at  the  present  terrestrial  fauna  of 
Australia,  it  appears  to  me  to  be  very  probable 
that  it  is  essentially  a  remnant  of  the  fauna  of  the 
Triassic,  or  even  of  an  earlier,  age ;  ^  in  which  case 
Australia  must  at  that  time  have  been  in  continuity 
with  the  Arctogseal  continent. 

But  now  comes  the  further  inquiry,  Where  was 
the  highly  differentiated  Sauropsidan  fauna  of  the 
Trias  in  Palaeozoic  times  ?  The  supposition  that 
the  Dinosaurian,  Crocodilian,  Dicynodontian,  and 
Plesiosaurian  types  were  suddenly  created  at  the 
end  of  the  Permian  epoch  may  be  dismissed,  with- 
out further  consideration,  as  a  monstrous  and  un- 
warranted assumption.  The  supposition  that  all 
these  types  were  rapidly  differentiated  out  of 
Lacertilia  in  the  time  represented  by  the  passage 
from  the  Palaeozoic  to  the  Mesozoic  formation, 
appears  to  me  to  be  hardly  more  credible,  to  say 
nothing  of  the  indications  of  the  existence  of 
Dinosaurian  forms  in  the  Permian  rocks  which 
have  already  been  obtained. 

For  my  part,  I  entertain  no  sort  of  doubt  that 
the  Reptiles,  Birds,  and  Mammals  of  the  Trias  are 
the  direct  descendants  of  Reptiles,  Birds,  and 
Mammals  which  existed  in  the  latter  part  of  the 

^  Since  this  Address  was  read,  Mr.  Krefft  has  sent  us  news  of 
the  discovery  in  Australia  of  a  freshwater  fish  of  straugily 
Palaeozoic  aspect,  and  apparently  a  Ganoid  intermediate  between 
Dipterus  and  Lepidosiren.  [The  now  well-known  Ceratodus. 189 'L.] 


XI  PALEONTOLOGY  AND   EVOLUTION  383 

Palaeozoic  epoch,  but  not  in  any  area  of  the  present 
dry  land  which  has  yet  been  explored  by  the 
geologist. 

This  may  seem  a  bold  assumption,  but  it  will 
not  appear  unwarrantable  to  those  who  reflect 
upon  the  very  small  extent  of  the  earth's  surface 
which  has  hitherto  exhibited  the  remains  of  the 
great  Mammalian  fauna  of  the  Eocene  times.  In  this 
respect,  the  Permian  land  Vertebrate  fauna  appears 
to  me  to  be  related  to  the  Triassic  much  as  the 
Eocene  is  to  the  Miocene.  Terrestrial  reptiles 
have  been  found  in  Permian  rocks  only  in  three 
localities ;  in  some  spots  of  France,  and  recently 
of  England,  and  over  a  more  extensive  area  in 
Germany.  Who  can  suppose  that  the  few  fossils 
yet  found  in  these  regions  give  any  sufficient  re- 
presentation of  the  Permian  fauna  ? 

It  may  be  said  that  the  Carboniferous  forma- 
tions demonstrate  the  existence  of  a  vast  extent 
of  dry  land  in  the  present  dry-land  area,  and  that 
the  supposed  terrestrial  Palaeozoic  Vertebrate 
Fauna  ought  to  have  left  its  remains  in  the  Coal- 
measures,  especially  as  there  is  now  reason  to 
believe  that  much  of  the  coal  was  formed  by  the 
accumulation  of  spores  and  sporangia  on  dry  land. 
But  if  we  consider  the  matter  more  closely,  I 
think  that  this  apparent  objection  loses  its  force. 
It  is  clear  that,  during  the  Carboniferous  epoch, 
the  vast  area  of  land  which  is  now  covered  by 
Coal-measures  must  have  been  undergoing  a 
gradual  depression.     The  dry  land  thus  depressed 


884  PALEONTOLOGY   AND   EVOLUTION  xi 

must,  therefore,  have  existed,  as  such,  before  the 
Carboniferous  epoch — in  other  words,  in  Devonian 
times — and  its  terrestrial  population  may  never 
have  been  other  than  such  as  existed  during  the 
Devonian,  or  some  previous  epoch,  although  much 
higher  forms  may  have  been  develoiDed  else- 
where. 

Again,  let  me  say  that  I  am  making  no 
gratuitous  assumption  of  inconceivable  changes. 
It  is  clear  that  the  enormous  area  of  Polynesia  is, 
on  the  whole,  an  area  over  which  depression  has 
taken  place  to  an  immense  extent ;  consequently 
a  great  continent,  or  assemblage  of  subcontinental 
masses  of  land  must  have  existed  at  some  former 
time,  and  that  at  a  recent  period,  geologically 
speaking,  in  the  area  of  the  Pacific.  But  if  that 
continent  had  contained  Mammals,  some  of  them 
must  have  remained  to  tell  the  tale ;  and  as  it  is 
well  known  that  these  islands  have  no  indigenous 
Mammalia,  it  is  safe  to  assume  that  none  existed. 
Thus,  midway  between  AustraHa  and  South 
America,  each  of  which  possesses  an  abundant 
and  diversified  mammahan  fauna,  a  mass  of  land, 
which  may  have  been  as  large  as  both  put  together, 
must  have  existed  ^vithout  a  mammalian  in- 
habitant. Suppose  that  the  shores  of  this  great 
land  were  fringed,  as  those  of  tropical  Australia  are 
now,  with  belts  of  mangroves,  which  would  extend 
landwards  on  the  one  side,  and  be  buried  beneath 
littoral  deposits  on  the  other  side,  as  depression 
went   on;    and   great  beds  of  mangrove  lignite 


XI  PALEONTOLOGY   AND   EVOLUTION  885 

might  accumulate  over  the  sinking  land.  Let 
upheaval  of  the  whole  now  take  place,  in  such  a 
manner  as  to  bring  the  emerging  land  into  con- 
tinuity with  the  South- American  or  Austrahan 
continent,  and,  in  course  of  time,  it  would  be 
peopled  by  an  extension  of  the  fauna  of  one  of 
these  two  regions — ^just  as  I  imagine  the  European 
Permian  dry  land  to  have  been  peopled. 

I  see  nothing  whatever  against  the  supposition 
that  distributional  provinces  of  terrestrial  life 
existed  in  the  Devonian  epoch,  inasmuch  as  M. 
Barrande  has  proved  that  they  existed  much 
earlier.  I  am  aware  of  no  reason  for  doubting 
that,  as  regards  the  grades  of  terrestrial  life 
contained  in  them,  one  of  these  may  have  been 
related  to  another  as  New  Zealand  is  to  Australia, 
or  as  Australia  is  to  India,  at  the  present  day. 
Analogy  seems  to  me  to  be  rather  in  favour  of, 
than  against,  the  supposition  that  while  only 
Ganoid  fishes  inhabited  the  fresh  waters  of  our 
Devonian  land,  Amiohibia  and  Reptilia,  or  even 
higher  forms,  may  have  existed,  though  we  have 
not  yet  found  them.  The  earliest  Carboniferous 
AmpJiihia  now  known,  such  as  Anthraccsaurus, 
are  so  highly  specialised  that  I  can  by  no  means 
conceive  that  they  have  been  developed  out  of 
piscine  forms  in  the  interval  between  the  Devonian 
and  the  Carboniferous  periods,  considerable  as  that 
is.  And  I  take  refuge  in  one  of  two  alternatives  ; 
either  they  existed  in  our  own  area  during  the 
Devonian  epoch  and  we  have  simply  not  yet  found 

211 


386  PALEONTOLOGY   AND   EVOLUTION  xi 

them;  or  they  formed  part  of  the  population  of 
some  other  distributional  province  of  that  day, 
and  only  entered  our  area  by  migration  at  the  end 
of  the  Devonian  epoch.  Whether  Be2:)tilia  and 
Mammalia  existed  along  with  them  is  to  me,  at 
present,  a  perfectly  open  question,  which  is  just 
as  likely  to  receive  an  affirmative  as  a  negative 
answer  from  future  inquirers. 

Let  me  now  gather  together  the  threads  of  my 
argumentation  into  the  form  of  a  connected  hypo- 
thetical view  of  the  manner  in  w^hich  the  dis- 
tribution of  living  and  extinct  animals  has  been 
brought  about. 

I  conceive  that  distinct  provinces  of  the  distribu- 
tion of  terrestrial  life  have  existed  since  the  earliest 
period  at  which  that  life  is  recorded,  and  possibly 
much  earlier;  and  I  suppose,  with  Mr.  Darwin, 
that  the  progress  of  modification  of  terrestrial 
forms  is  more  rapid  in  areas  of  elevation  than  in 
areas  of  depression.  I  take  it  to  be  certain  that 
Labyrinthodont  Amphibia  existed  in  the  distribu- 
tional province  which  included  the  dry  land 
depressed  during  the  Carboniferous  epoch  ;  and 
I  conceive  that,  in  some  other  distributional 
provinces  of  that  day,  which  remained  in  the 
condition  of  stationary  or  of  increasing  dry  land, 
the  various  types  of  the  terrestrial  Sattrcjysida 
and  of  the  Mavimalia  were  gradually  developing. 

The  Permian  epoch  marks  the  commencement 
of  a  new  movement  of  upheaval  in  our  area,  which 
attained  its  maximum  in  the  Triassic  epoch,  when 


XI  PAX^ONTOLOGY   AND   EVOLUTION  387 

dry  land  existed  in  North  Ameiica,  Europe,  Asia, 
and  Africa,  as  it  does  now.  Into  this  great  new 
continental  area  the  Mammals,  Birds,  and  Rejjtiles 
developed  during  the  Palaeozoic  epoch  spread,  and 
formed  the  great  Triassic  Arctoga^al  province. 
But,  at  the  end  of  the  Triassic  period,  the  move- 
ment of  depression  recommenced  in  our  area, 
though  it  was  doubtless  balanced  by  elevation 
elsewhere  ;  modification  and  development,  checked 
in  the  one  province,  went  on  in  that "  elsewhere  "  ; 
and  the  chief  forms  of  Mammals,  Birds  and  Rep- 
tiles, as  we  know  them,  were  evolved  and  peopled 
the  Mesozoic  continent.  I  conceive  Australia  to 
have  become  separated  from  the  continent  as  early 
as  the  end  of  the  Triassic  epoch,  or  not  much 
later.  The  Mesozoic  continent  must,  I  conceive, 
have  lain  to  the  east,  about  the  shores  of  the 
North  Pacific  and  Indian  Oceans ;  and  I  am 
inclined  to  believe  that  it  continued  along  the 
eastern  side  of  the  Pacific  area  to  what  is  now  the 
province  of  Austro-Columbia,  the  characteristic 
fauna  of  which  is  probably  a  remnant  of  the  popu- 
lation of  the  latter  part  of  this  period. 

Towards  the  latter  part  of  the  Mesozoic 
period  the  movement  of  upheaval  around  the 
shores  of  the  Atlantic  once  more  recommenced, 
and  was  very  probably  accompanied  by  a  de- 
pression around  those  of  the  Pacific.  The  Verte- 
brate fauna  elaborated  in  the  Mesozoic  continent 
moved  westward  and  took  possession  of  the  new 


388  PAL^:ONTOLOGY   AND   EVOLUTION  jj 

lands,  which  gradually  increased  in  extent  up  to, 
and  in  some  directions  after,  the  Miocene  epoch. 

It  is  in  favour  of  this  hypothesis,  I  think, 
that  it  is  consistent  with  the  persistence  of  a 
general  uniformity  in  the  positions  of  the  great 
masses  of  land  and  water.  From  the  Devonian 
period,  or  earlier,  to  the  present  day,  the  four 
great  oceans,  Atlantic,  Pacific,  Arctic,  and  Antarc- 
tic, may  have  occupied  their  present  positions, 
and  only  their  coasts  and  channels  of  communi- 
cation have  undergone  an  incessant  alteration. 
And,  finally,  the  hypothesis  I  have  put  before  you 
requires  no  supposition  that  the  rate  of  change  in 
organic  life  has  been  either  greater  or  less  in 
ancient  times  than  it  is  now  ;  nor  any  assumption, 
either  physical  or  biological,  which  has  not  its 
justification  in  analogous  phenomena  of  existing 
nature. 

I  have  now  only  to  discharge  the  last  duty 
of  my  office,  which  is  to  thank  you,  not  only 
for  the  patient  attention  with  which  vou  have 
listened  to  me  so  long  to-day,  but  also  for  the 
uniform  kindness  with  which,  for  the  past  two 
years,  you  have  rendered  my  endeavours  to  per- 
form the  important,  and  often  laborious,  functions 
of  your  President  a  pleasure  instead  of  a  burden. 

END   OF  VOLUME   VII  I. 


:l^->:; 

